Teachers want homework to be abolished for primary school age children.
The amount of homework set is often an issue for parents
A motion for the Association of Teachers and Lecturers conference will also seek a Royal Commission to examine why children are unhappy at school.
Union leader Mary Bousted said the difficulty of completing homework could set up a cycle of resistance to school in children from poorer homes.
The government says that homework is not compulsory but it is encouraged as a key part of the learning process.
Its guidelines for schools in England say children should be doing homework from the day they start school, rising from one hour a week at five, to 90 to 150 minutes a day at 16.
They say 10 and 11-year-olds should be doing half an hour of homework every day.
But research has cast doubt on its effectiveness, and has even suggested that too much is counter-productive.
Some independent schools have abolished the practice.
Dr Bousted told journalists that in state schools everyone just accepted that homework had to be done.
"I think a lot of homework is a waste of time. The teacher has got to set it, so what gets set is 'busy' homework," she said.
But children from disadvantaged homes, who did not have the resources and support middle class parents provided, could get into trouble for not completing it.
"I think it sets up a cycle of resistance to school because they don't have access to the cultural and emotional and learning support which middle-class children can get."
The motion also says many children appear "unhappy and anxious".
"Children should be able to explore, experiment and enjoy their learning without feeling pressurised," it adds.
"Homework has become an increasing pressure placed on children in primary and secondary schools."
The motion wants ministers to "scrap compulsory homework for primary-aged children and to limit the amount of time allocated to compulsory homework at secondary level".
'Most are happy'
A spokesman for the Department for Children, Schools and Families said homework was not compulsory but it encouraged teachers to set children work to do at outside the classroom.
"We have clear guidance for teachers on their legal entitlement to set homework.
"A good, well-organised homework programme helps children and young people to develop the skills and attitudes they will need for successful, independent, lifelong learning.
"Research shows that for most children, 2008 is a great time to be a child. Most children are happy, most are achieving to a higher level than ever before, enjoying better health, more opportunities to travel, to engage in sport or cultural activities than was the case for any previous generation."
The government has a new Children's Plan for England - underpinned by a study of parents which said they felt there was something fundamentally wrong with modern childhood.