Students from 12,000 schools nationwide will be told not to do their weekend homework for the month of November.
The Spanish Alliance of Parents' Associations (CEAPA), which called the strike, argues that homework is detrimental to children.
Spain was high up on a homework league table in a 2012 education report.
The PISA study, by the Organisation for Economic Co-operation and Development, found that Spanish children and teenagers have 6.5 hours of homework a week, compared with an average of 4.9 from a group of 38 countries.
Spain ranked 11th on a list of 64 countries or locations in a PISA table covering the amount of homework given.
The workload does not necessarily translate in better results for Spanish students - they have traditionally scored low results in maths, reading and science in other PISA reports.
By contrast, in Finland and South Korea, two of the countries with the best student performances according to PISA - the average time spent on homework every week was less than three hours.
So what does this say about the learning methods used in Spain?
CEAPA president Jose Luis Pazos says education in Spain has been very reliant on the traditional method of rote-learning - memorising work.
He stresses that what children have to learn is how to manage information and how to decide what to memorise and what not.
"Society has changed deeply, but the environment in the classroom hasn't," he says.
The homework debate has been raging in other countries too, and it is not just parents who are concerned.
In the US state of Texas, a secondary school teacher near Dallas sent a letter to parents telling them that she will not be assigning homework to students this year. Instead, she said she wanted them to spend more time with their families.
A high school in Britain scrapped traditional homework at the start of term in favour of a more "independent" approach to learning.
And even in South Korea, the authorities are considering reducing homework for younger pupils even further. The Yonhap news agency reported in August that the city education office in Seoul was banning primary schools from giving homework to lower grade students, starting next year.
Thousands of parents in Spain are going on strike against state schools this weekend over the large amount of homework given to their children.