Objective: To study the change of daily blood drug concentration in patients with mental illness after taking quetiapine and its influencing factors on clinical efficacy, and to provide a reference for the rational use of quetiapine in clinic. Methods: Data of 786 cases of mental patients treated with quetiapine from January to December 2018 were extracted. The results of routine blood concentration test of quetiapine, gender, age and dose of the patients were calculated, and the relationship between blood concentration of quetiapine, gender, age and dose were analyzed. Results: The most common dose of quetiapine was between 0 and 150 mg, everday (25.45%), and then was between 150 and 300 mg,(24.43%), 450 and 600 mg (21.76%), 300 and 450 mg, everday (11.96%), and 4 doses accounted for 83.60% of the total constituent ratio. The plasma concentration of quetiapine was mainly concentrated between 0 and 150 ng/mL (57.76%), and then between 150 and 300 ng/mL (30.28%), and 2 concentrations accounted for 88.04% of the total composition ratio. The average plasma concentrations of the patients were increased with the increase of the dosage, and the concentration-dosage ratios were reduced with the increase of the dosage. With the increase of age, the concentration-dosage ratios showed an increasing trend. Conclusion: The monitoring of the daily blood drug concentration of quetiapine can not only promote the better clinical efficacy of drugs, but also can promote the rational use of antipsychotic drugs, and at the same time can avoid or reduce the occurrence of adverse reactions.