Introduction: How the launch delay of drugs and other factors of interest can influence the length of the review period by drug agencies is still unknown, and understanding this can help better strike the trade-off related to review speed. Methods: We included all new oncology drug applications submitted to China's National Medical Product Administration (NMPA) between 1 January 2018 and 31 December 2021, and ultimately succeeded in achieving marketing approval. For each drug, the length of the NMPA review process and other major characteristics were collected, including the registration class, approval class, priority review designation, and launch delay relative to the United States, as well as the number of patients enrolled, comparator, and primary endpoint of the pivotal trials supporting the approval. Linear regression model was employed to analyze the effects of factors of interest on the NMPA review time. Results: From 2018 to 2021, NMPA received 137 oncology applications that were ultimately approved. Half of the approvals [76 (55.5%)] were first licensed in the US, leaving a median launch delay of 2.71years (IQR, 1.03-5.59) in China. In the pivotal studies, the median enrollment was 361 participants (IQR, 131-682), and the use of control groups [90 (65.7%)] and surrogate endpoints [101 (73.7%)] was prevalent. The median review time was 304days (IQR, 253-376). Multivariate analysis for log-transformed review time showed that larger enrollment ( 92) was associated with a drop of 20.55% in review time (coefficient = -0.230; 95% CI, -0.404 to -0.055; p = 0.010); and a short delay (0 delay 1.95years) was associated with a drop of 17.63% in review time (coefficient = -0.194; 95% CI, -0.325 to -0.062; p = 0.004). Discussion: The short launch delay relative to the US was one important driver to the review speed of NMPA, which might suggest its latent regulatory reliance on the other global regulator during the post-marketing period when new information on the drug's clinical benefit was still lacking.