In this paper, we present the analytical solution of the Fokker-Planck equation of non-degenerate optical parametric amplification(NOPA)for generation of squeezed light. The maximum intra-cavity compression of squeezed light derived from the analytical solution is 1/16(vacuum fluctuations 1/4). To compare it with that of the previous result 1/8 of degenerate optical parametric amplification(DOPA), it seems that the squeezing for NOPA is superior to the squeezing for DOPA.