In order to conserve paintings and colored drawings scientifically,an investigation has been carried out on representative paintings and colored drawings of Xi'an Drum Tower.It has been shown that the main deterioration problems are gloss loss,color fading or changing,powdering,cracking,peeling,falling,smoke damage,dust,etc.Preliminary deterioration causes were discussed based on simulation experiments.The results indicated that wood moisture content and plastering techniques were the internal causes leading to deterioration.External environmental factors include ultraviolet radiation,temperature and humidity,atmospheric dust, smoke and rain,etc.The results provide scientific bases for the protection of paintings and colored drawings.