The new government, led by Stefan Löfven's Social Democrats and the Green Party (Miljöpartiet) presented its first joint proposal since winning the election earlier this month.
Both parties agreed at the weekend that compulsory schooling should be extended, teacher salaries should be increased, and class sizes made smaller.
"We can't give the idea to young people that there are jobs available for people without high-school education," Green Party co-spokesperson Gustav Fridolin told the TT news agency.
"Those jobs simply don't exist anymore."
School is currently only compulsory until the age of 16.
It remains unclear exactly when the proposed changes will come into effect.
Sweden's education system has come under harsh criticism since April, when Swedish pupils' results in the global Pisa education ranking pushed Sweden below the OECD average in maths, reading comprehension, and natural sciences.
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