Based on precipitation data from CRU TS v4.0 (Climatic Research Unit Time series 4.0) and 24 CMIP5 (Coupled Model Intercomparison Project Phase 5) historical experimental models and the RCP4.5 (Representative Concentration Pathway 4.5) scenario, this paper analyzed the bias and its correction method in precipitation projected by the ensemble of the CMIP5 multi-models. Bias of precipitation estimated over China for 2006-2015 under the RCP4.5 scenario was corrected by removing its climate drift and univariate logarithmic difference regression equation. Results showed that the model precipitation was usually overestimated in western and northern parts of China, while it was underestimated in the southeast coastal zone. In the warm season (May-October), the model precipitation was underestimated in the southeast coastal monsoon zone, while it was significantly overestimated in the cold season (November-April). 84% precipitation deviations simulated by the historical experiment from 1956 to 2005 belonged to climate drift, the rest to unsteady modes. Bias of model precipitation was decreased by about 90% after removal of climate drift, and the anomaly percentage in most areas was within ±5%. Model precipitation was overestimated 10%-40% in the western Tibetan Plateau and the middle northwestern region. Distribution of precipitation anomaly was similar to annual precipitation in warm season. The deviation of the cold season was larger, with more precipitation in the north and less in the south. The model was improved in its coincidence rate of anomaly sign after correction by using single linear logarithmic increment regression. The drought and reduced rain in the southwestern and central parts of the regions south of the Yangtze River reappeared during the period from 2006 to 2015, although the standard deviation was larger than the correction of climate drift. After the correction by SR-Log-Increment, the projected precipitation for 2016-2035 under RCP4.5 scenario showed that the precipitation would increase in the northeastern part of the south, the Huaihe River basin, and most parts of the northwest by about 10%-40%. Over the southeast coast and Taiwan, precipitation increased by about 10%-20%. It decreased in the south of the Huaihe River by about 5%-20%, while in Hetao, Inner Mongolia, and north of Northern China, the decrease was about 20%-40%. Results implied that under the RCP4.5 scenario, the southwest drought would be slightly relieved in the early 21st century, while there would be little change in the pattern of less precipitation in the south. Also, precipitation would increase significantly in the Huaihe River basin, the source of the three rivers, and its western region. Distribution of the precipitation anomaly over mainland China would present a pattern of less precipitation in the south and north, with more in the middle. Nevertheless, the projection of precipitation in the northern and western alpine regions had clear uncertainty.