Abstract: OBJECTIVE Quantitative analysis of crystal type Ⅰ content in atorvastatin calcium tablets was established by powder X-ray diffraction. METHODS The linear equation of crystal type Ⅰ content y=3 179.3x-304.56(r=0.992 3) was established by the method of shorting the scan range, decreasing the scan speed and improving the step scan time, the methods was validated by methodology. RESULTS The six batches containing two specifications of crystal typeⅠcontent in atorvastatin calcium tablets were determinated, the results showed that the crystal typeⅠcontent has certain changes. CONCLUSION The method was simple in operation, which can be used in quantitative analysis of crystal type Ⅰ content in atorvastatin calcium tablets under no interference with excipients.