Objective To explore the CT features of renal colic caused by unilateral ureteral calculi. Methods 78 patientswith unilateral ureteral calculi who were treated in our hospital from December 2013 to January 2017 were selected as the subjects,set it as observation group,in the same period, 78 healthy volunteers were recruited as control group.At the same time, according to the size of the stones, the observation group was divided into larger group (21 cases), medium group (n=34) and group (n=23). According to the location of the stones, the observation group was divided into upper ureter group (11 cases), middle ureter group (n=26) and lower ureter group (n=41).According to the degree of pain, the patients were divided into mild group (24 cases), moderate group (n=23) and severe group (n=31). Finally, according to the measurement of the ratio of CT to 100% (CT value of double kidney), the factors affecting the degree of renal colic pain were analyzed. Results The study found that there was no significant difference in the CT ratio between the larger, middle and small groups (P>0.05), and all were less than the control group, the difference was statistically significant (P<0.05). There was no significant difference in CT ratio between the upper ureteral group, the middle ureteral group and the lower ureteral segment (P>0.05), and all were less than the control group, the difference was statistically significant (P<0.05). In mild group, the CT ratio was higher than that in moderate group and severe group, and the ratio of CT between the two groups was higher than that in severe group (P<0.05). Conclusion Unilateral ureteral calculi lead to renal colic,the CT ratio of the two kidneys did not determine the size of the stones and the location of the stones, but to a certain extent, the degree of pain could be predicted.