The move could sound the death knell for the Sats, which are taken by about 1.2 million primary school children a year.
Despite a warning from the Government that a boycott would be "unlawful", more than 1,000 delegates at the National Union of Teachers annual conference in Cardiff yesterday passed the motion unanimously, to a standing ovation.
Members want the tests to be replaced by teacher assessment, and the school league tables - which are based on Sats results - scrapped.
They claim that the tests damage children's education because there is too much narrow "teaching to the test", with pupils cramming for the papers months before they sit them.
Other subjects are squeezed out of the curriculum and teachers and pupils are placed under unacceptable pressure, they claim.
The National Association of Head Teachers (NAHT), which represents 85 per cent of primary heads, will vote next month on a boycott.
The joint action, to start next year, will escalate tensions between the Government and the teaching profession and comes just weeks before the start of this year's Sats in English, maths and science for 11 year olds, which start on May 11.
Hazel Danson, a primary school teacher from Kirklees who proposed the motion, told the conference: "This is an unprecedented move to get rid of these damaging tests.
"We represent the majority of teachers and heads in primary schools and that is a formidable force. We will be heard. It is a fatally flawed system and we would be reckless and irresponsible if we allowed the system in primary schools to remain."
Teachers went as far as describing the tests as "child abuse".
Max Hyde, a member of the NUT executive, said: "At best Sats are detrimental and skew the curriculum, at worst, and particularly for our most vulnerable children, they are perilously close to child abuse."
Christine Blower, the acting general secretary, said after the vote that the union was prepared to negotiate with ministers to avoid the need for action. "That is why we're giving so much notice of our intentions," she said.
She also said that parents supported scrapping Sats, quoting an NAHT survey of 10,000 parents which found that 85 per cent wanted to abolish the current system.
The Department for Children, Schools and Families had urged NUT members not to vote in favour in the ballot. It said any attempt to boycott the tests was "unlawful" and risked "removing a basic right" of parents to see how their children and local schools were performing.
However, comments made by Ed Balls, the children's secretary, last week, suggested the Government was not completely wedded to the current system. It has already scrapped tests for 14-year-olds.
Mr Balls said he would act on the recommendations of the experts group on testing, convened after last summer's Sats fiasco, which is due to report next month.
But he warned that any reform would not be introduced until 2011 at the earliest. He said the government had "no intention of getting rid of testing altogether" and that a boycott would be "irresponsible and disruptive".
Despite widespread concerns about the affects of the tests on teaching and children's stress levels, the boycott plan has failed to win the unanimous backing of other teachers leaders.
Mary Bousted, the general secretary of the Association of Teachers and Lecturers, said it was the wrong way to proceed.
"The idea that a boycott will sway the government is naive," she said. "If anything, it is likely to make it more intransigent."
Chris Keates, general secretary of the NASUWT, said the entire school accountability regime needed to be radically overhauled.
"Simply removing the tests will do teachers no favours at all," she added. "The important thing is to get rid of league tables."
Heads have a statutory responsibility to administer key stage tests but union legal experts said they were confident that members would not face contractual problems if a boycott went ahead.
School governors, however, have warned that a boycott could lead to disciplinary action.
Phil Revell, chief executive of the National Governors' Association, said: "We really regret that head teachers are going down the road of a boycott. Governors will make it absolutely clear that undue pressure brought on any teacher who wishes to administer the test will result in disciplinary action. It is completely different for a head, as opposed to a teacher, to take this form of action." (By Julie Henry, Education Correspondent Last Updated: 11:14PM BST 11 Apr 2009)