A novel photochromic diarylethene based on pyrazole moiety was synthesized and its photochromic and fluorescent properties were also investigated. The compound exhibited remarkable photochromism, changing from colorless to purple after irradiation with UV light both in solution and in PMMA film. In hexane solution and in PMMA film, the open-ring isomer of the diarylethene 1 exhibited relatively remarkable fluorescence. The results indicated that the pyrazole moiety played a very important role during the process of photochromic reaction for the diarylethene derivative. Using this dithienylethene 1c as optical storage was performed successfully.