The length of waiting time has become an important indicator of the efficiency of medical services and the quality of medical care. Lengthy waiting times for patients will inevitably affect their mood and reduce satisfaction. For patients who are in urgent need of hospitalization, delayed admission often leads to exacerbation of the patient’s condition and may threaten the patient’s life. We gathered patients’ information about outpatient visits and hospital admissions in the Nephrology Department of a large tertiary hospital in western China from January 1st, 2014, to December 31st, 2016, and we used big data-enabled analysis methods, including univariate analysis and multivariate linear regression models, to explore the factors affecting waiting time. We found that gender (
P
=
0.048
), the day of issuing the admission card (Saturday,
P
=
0.028
), the applied period for admission (
P
<
0.001
), and the registration interval (
P
<
0.001
) were positive influencing factors of patients’ waiting time. Disease type (after kidney transplantation,
P
<
0.001
), number of diagnoses (
P
=
0.037
), and the day of issuing the admission card (Sunday,
P
=
0.001
) were negative factors. A linear regression model built using these data performed well in the identification of factors affecting the waiting time of patients in the Nephrology Department. These results can be extended to other departments and could be valuable for improving patient satisfaction and hospital service quality by identifying the factors affecting waiting time.