The initial mass function ( IMF ) is an essential tool with which to study star formation processes .
We have initiated the photometric survey of young open clusters in the Galaxy , from which the stellar IMFs are obtained in a homogeneous way .
A total of 16 famous young open clusters have preferentially been studied up to now .
These clusters have a wide range of surface densities ( \log \sigma = -1 to 3 [ stars pc ^ { -2 } ] for stars with mass larger than 5 M _ { \odot } ) and cluster masses ( M _ { \mathrm { cl } } = 165 to 50 , 000 M _ { \odot } ) , and also are distributed in five different spiral arms in the Galaxy .
It is possible to test the dependence of star formation processes on the global properties of individual clusters or environmental conditions .
We present a preliminary result on the variation of the IMF in this paper .