Objective To investigate the therapeutic efficacy of granulocyte colony-stimulating factor in combination with tadalafil in patients with thin endometrium undergoing artificial cycle frozen-thawed embryo transfer （FET）. Methods A prospective randomized clinical trial was conducted involving sixty patients with thin endometrium who underwent artificial cycle FET at the Reproductive Center of Qinhuangdao First Hospital between January 2021 and October 2023. The patients were randomly assigned to two groups： the control group （n = 30） received tadalafil， while the study group （n = 30） received granulocyte colony-stimulating factor in addition to tadalafil. Endometrial ultrasound characteristics， uterine artery blood flow parameters， and pregnancy outcomes were compared between the two groups before and after treatment. Results Before treatment， no significant differences were observed between the research group and the control group in terms of endometrial thickness or endometrial volume （P > 0.05）. Ultrasound assessments were repeated after 8 and 14 days of treatment. Compared with baseline measurements， both endometrial thickness and volume exhibited significant increases in both groups （all P < 0.05）. By day 14 post-treatment， the research group demonstrated significantly greater endometrial thickness and volume compared to the control group （P < 0.05）. With regard to endometrial patterns， no significant differences were noted between the two groups prior to treatment （P > 0.05）. After 14 days of treatment， the proportion of patients exhibiting a Type A endometrial pattern in the research group was significantly higher than that in the control group （P < 0.05）. Prior to treatment， no statistically significant differences were observed between the two groups in terms of pulsatility index （PI）， resistance index （RI）， systolic/diastolic ratio （S/D）， vascularization index （VI）， flow index （FI）， or Vascularization Flow Index （VFI） （all P > 0.05）. Following 14 days of treatment， both groups showed significant increases in VI， FI， and VFI compared to baseline values （all P < 0.05）， along with significant reductions in PI， RI， and S/D （all P < 0.05）. At 14 days post-treatment， the S/D ratio in the research group was significantly lower compared to the control group， while the VFI was significantly higher （P < 0.05）. However， statistical analysis showed no significant differences between the two groups in terms of embryo implantation rate， clinical pregnancy rate， early miscarriage rate， and live birth rate （P > 0.05）. Conclusion For patients with thin endometrium undergoing FET， the combination of granulocyte colony-stimulating factor and tadalafil is more effective than tadalafil alone in improving endometrial receptivity and uterine blood perfusion.