The present invention discloses an antineoplastic sterile lyophilized powder of lentinan and the process of preparation thereof. The lyophilized powder of lentinan is essentially consisted of 0.50 1.40 parts of lentinan and 50 140 parts of excipient for lyophilization, based on weight. It has good stability. It has improved safety as it does not contain dextran which may cause allergic side effect.