Objective To study application effect of adaptive statistical iterative reconstruction (ASIR) technique combined with low dose CT scan in the diagnosis of urinary calculus. Methods 74 cases suspected clinically as urinary calculus in our hospital from December 2013 to December 2015 were divided by random lot method into two groups (each 37 cases), patients who underwent 130kV, 250mAs conventional dose scan were marked as conventional dose group, patients who underwent 130kV, 30mAs low dose scan were marked as low dose group, filtered back projection technique (FBP) and different weights ASIR were used to reconstruct and analyze images, CT scan calculus detection rate, diagnostic sensitivity, specificity, image quality, image noise score in the two groups were compared, radiation dose after CT scan in the two groups were compared. Results Detection rate of calculus in conventional dose group was 100%, detection rate of calculus in low dose group was 98.10%, FBP image quality score in conventional dose group was significantly higher than low dose group FBP, 20%ASIR, 40%ASIR image quality score (P<0.05), FBP image noise score in conventional dose group was significantly lower than low dose group FBP, 20%ASIR, 40%ASIR image noise score (P<0.05), CTDIvol, DLP, ED level after CT scan in conventional dose group were significantly higher than low dose group (P<0.05). Conclusion Low dose CT scan can reduce radiation dose of patients significantly, application of ASIR technique combined with low dose CT scan can improve image quality significantly, reduce image noise, provide valuable data for clinical diagnosis of urinary calculus, clinical feasibility is high.