Objective To explore the application value of low dose multi-slice spiral CT (MSCT) in the diagnosis of renal and ureteral calculi. Methods 69 patients with renal and ureteral calculi admitted to our hospital from January 2017 to June 2018 were selected. All the patients underwent low-dose scanning and routine CT non-enhanced scanning The presence, size, location and number of calculi in 69 patients were observed, the sensitivity and specificity of kidney and ureteral calculi diagnosed by low-dose scanning were calculated, and the radiation dose levels of the two scanning methods were compared. Results The results of routine CT scan showed that there were 41 cases of renal calculi, a total of 63 calculi, and 28 cases of ureteral calculi, a total of 38. Stone diameter: 54 stones diameter <0.5cm, 23 stones diameter 0.5-1.0cm, 24 stones diameter >1.0cm. A total of 98 stones were detected by low-dose CT examination, of which 52 stones were <0.5cm in diameter, 22 stones were 0.5-1.0cm in diameter, and 24 stones were >1.0cm in diameter. Compared with the low-dose CT scan, the number of kidney and ureteral calculi with different diameters was not statistically significant (χ2=3.045, P=0.081). The sensitivity and specificity of low-dose CT scanning in the diagnosis of renal calculi were 93.65% (59/63), 92.06% (58/63), and the sensitivity and specificity of the diagnosis of ureteral calculi were 92.10% (35/38) and 94.73% (36/38), respectively. The radiation dose of conventional CT non-enhanced scan was (10.25±2.41) mGy·cm, significantly higher than that of low-dose CT (3.61±1.01), and the difference had statistical significance (P<0.001). Conclusion Multi-slice spiral CT with low dose has high detection rate, sensitivity and specificity for renal and ureteral calculi, which can effectively reduce radiation dose and is worthy of clinical promotion.