With the aid of c-number Langevin equations, we have calculated the Q-functions forrnthe two-mode coherent and subharmonic cavity light beams. Applying the input-outputrnrelation, we have obtained the Q-functions for the two-mode coherent and subharmonicrnoutput light beams. We have then determined the Q-function for the superposition ofrnthese two output light beams. With the help of the pertinent Q-functions for the outputrnlight, we determined the output photon statistics. We have calculated the mean and vari-rnance of the photon number sum and di erence for the two-mode coherent output light,rnthe two-mode subharmonic output light, and the superposed two-mode coherent and sub-rnharmonic output light beams.rnWe have found that photon stastics of the two-mode coherent output light is Pois-rnsonian and that of the subharmonic output light is super Poissonian. And the outputrnsignal and idler modes are separately in a chaotic states. In addition, the mean photonrnnumber for the superposed output light turns out to be the sum of the mean photonrnnumber of the two-mode coherent output light and that of the two-mode subharmonicrnoutput light