Abstract: By restricting the common replacement axiom schema of ZF to ∑M-formulae,Professor Zhang Jinwen constructed a series of subsystems of Zennelo-Frankel set theory ZF and he called themZFM. Zhao Xi shun show that the consistency of ZFM can be deducted from ZF. Professor ZhangJinwen raised the question whether the consistency of ZFM can be deducted from ZF^M+m（M） for somem（n）≥1. In this paper,we get a positive solution to Professor Zhang's problem.Moreover,weshow that the consistency of ZFM can be deducted from ZF^M+3. 

Key words: set theory, consistency, reflection, truth defintion