Abstract: Hu Sheng pointed out that the purpose of the history studying of the Communist Party of China in socialist period is to prove the correctness of the socialist road with Chinese characteristics.The history of the party in socialist period can be divided into two major periods:before and after the Third Plenary Session of the Eleventh Party Central Committee.He analysed the historical development of the party in socialist period with "two developing trends".The cause of the "left" errors is that the experience of the mass struggle and the class struggle of the Chinese revolution is mistakenly used.The experience of socialist construction is that the road of socialist construction with Chinese characteristics can be explored on the basis of experience of the success and failure,according to the principle of combining Marxism with Chinese specific situation.