In monogastric animals the ability of digesting phytase is lacking which hydrolysis phytate to release phosphate. This paper concentrates on the commercial production of phytase which replenish the need of phosphate in livestock feed production. Response surface methodology was applied for the optimization of phytase production by Hypocrea lixii SURT01. Four factors such as carbon source (sucrose), nitrogen source (peptone), substrate (phytate) in different concentration and pH were optimized using central composite design (CCD). The optimum levels of variables that supported maximum enzyme activity were 1.5% sucrose, 0.2% phytate, 3% peptone and pH 7.5. The validity of the model in optimized conditions was verified. With this composition, the phytase production was 74.56IU (average of three repeats) after 96 h of cultivation, while the predicted maximum production was 73.42 IU. The optimized medium resulted in significant increase of the phytase yield by Hypocrea lixii in shake-flask cultivation.