Phosphorus forms of black soils from different cultivation years in four regions of Heilongjiang Province were investigated in this paper. Results showed that with the increase in cultivation years the total-P content increased, and the content of organic phosphorus increased initially and decreased afterwards. However, the content of available-P, Al-P, Fe-P, Ca-P decreased first and then increased, while O-P content changed slightly. The order of various inorganic-P fractions was Fe-P>Ca-P>Al-P>O-P; and their change intensity was in the order of Fe-P>Ca-P>O-P>Al-P. For black soils under same cultivation year differing in erosion severity in Shuangcheng and Binxian counties, the contents of total-P, Al-P, Fe-P, O-P in eroded Binxian area were higher than those of non-eroded Shuangcheng area, and the contents of available-P and Ca-P in non-eroded area were greater than those of eroded area. From non-eroded area to eroded area, the change of various inorganic-P fractions was in the order of Fe-P>Ca-P>Al-P>O-P while the change intensity was in the order of Fe-P>Ca-P>Al-P>O-P. A significant correlation among organic-P, available-P and total-P was found. Ca-P, Al-P and O-P were effective sources of available phosphorus in these black soils.