Objective: To explore the function and molecular mechanism of Timeless in promoting hepatocellular carcinoma (HCC) growth. Methods: The expression of Timeless in HCC and paracancer tissues were analyzed by using the public data of HCC. Timeless was overexpressed in MHCC97L cells and silenced in MHCC97H cells, respectively, and the expression of Timeless and its downstream molecules were detected by real-time PCR and western blot. The effects of Timeless on cell glycolysis, oxidative phosphorylation and proliferation were detected by the glucose uptake experiment, lactic acid detection experiment, the extracellular fluid pH detection experiment, cell oxygen consumption test and cell viability assay, respectively. Results: The level of Timeless in HCC tissue was significantly higher than that of paracancer tissue (P<0.05). The relative cellular glucose uptake levels in the groups of Timeless knockdown, including siTimeless-1 and siTimeless-2 group were 0.510±0.119 and 0.508±0.099, respectively, significantly different from that of control group (P<0.05); The relative cellular uptake level of Timeless overexpressed group was 1.953±0.324, significantly different from that of vector transfected group (P<0.05). The relative levels of lactic acid production in the siTimeless-1 and siTimeless-2 group were 0.579±0.096 and 0.550±0.120, respectively, significantly different from that of control group (P<0.05); The relative production level of lactic acid in the Timeless overexpressed group was 1.463±0.179, significantly different that of vector transfected group (P<0.05). The extracellular pH values of siTimeless-1 and siTimeless-2 group were 7.390±0.035 and 7.370±0.060, respectively, significantly different from that of control group (P<0.05); the extracellular pH value of Timeless overexpressed group was 7.130±0.031, significantly different than vector transfected group (P<0.05). Oxygen consumption rate of siTimeless-1 and siTimeless-2 group were 3.686±0.389 and 3.955±0.431, respectively, significantly higher than 1.690±0.297 of control group (P<0.05); Oxygen consumption rate of Timeless overexpressed group was 1.302±0.336, significantly lower than 3.185±0.262 of vector transfected group (P<0.05) Timeless inhibited the expression of p53. The cell glucose uptake, lactic acid production, the pH of extracellular culture medium and cell oxygen consumption of control group were not significantly different from that of Timeless and p53 co-silenced group [(si-Timeless+sip53) group] (P>0.05); the glucose uptake, the production of lactic acid, the pH of the extracellular culture medium and the oxygen consumption of Timeless co-transfected with p53 (Timeless+p53) group were not significantly different from those of vector transfected group (P>0.05). Timeless promoted the proliferation of HCC cells through inhibiting the expression of p53. Conclusion Timeless promotes reprogramming of glucose metabolism and proliferation of HCC cells by inhibiting the p53-dependent signaling pathway.