A pool-culture experiment was conducted to study the effects of different subsoil bulk density at the depths of 20-40 and 40-60 cm on the late growth stage photosynthetic characteristics and grain yield of maize. The results showed that there existed significant differences in the net photosynthetic rate (Pn) and grain yield when the subsoil bulk density was differed. The Pn and grain yield decreased with increasing subsoil bulk density, and the higher the bulk density, the more significant the decrement in Pn and grain yield. The diurnal changes of Pn and intercellular CO2 concentration (Ci) were not in the same trend. Pn was high at noon and low at twilight and dusk, and decreased with increasing subsoil bulk density; while Ci was in adverse. The stomatal limitation (Ls) and stomatal conductance (Gs) also decreased with increasing subsoil bulk density. With the development of maize, the Pn, Ls and Gs, decreased gradually, while Ci increased continuously.