Mean daily maximum temperature (MDMT) is one of major indexes of heat resource. The previous models have been improved in this paper on the basis of previous studies. The influence of slope, aspect, and terrain inter-shielding on astronomical solar radiation over complex terrains (CT) is considered, and a distributed model, based on astronomical solar radiation over CT and the elevation height, the global solar radiation over CT, the sunshine percentage, for calculating monthly MDMT over CT is developed. Using this model, the elaborate distribution of monthly MDMT with a resolution of 100m×100m is generated by a DEM, meteorological observations data at 102 weather stations of the Guizhou province and surrounding area, observations data of NOAA-AVHRR and solar radiation data of 10 weather stations. The results are as follows: (1) The influence of the slope, aspect and terrain inter-shielding on spatial distribution of monthly MDMT is great. Due to the influence of local terrain factors, the spatial distribution of monthly MDMT over CT on Guizhou Plateau has obvious terrain distributing feature, and the effect of CT on monthly MDMT should be considered. (2) The effect of local terrain factors on spatial distribution of monthly MDMT over CT is different in different seasons, and it is greater in winter half year than in summer half year. The monthly MDMT decreases with the rise of above sea level. It increases with the slope accretion (decrease) on south (north)-central face of the mountain. The monthly MDMT increases from north-central face to south-central face of the mountain, and they are the highest (lowest) on south (north)-central face of the mountain from January to May and from October to December. It is opposite in July and August because of high solar altitude angle.