Since March of this year, our Reproductive Medicine Center has been using the modified extra-long protocol + blastocyst culture for freeze-thaw embryo transfer and has achieved a high clinical pregnancy rate of 70-80%. Especially for repeated failure of implantation, thin endometrium and post-operative cavity adhesions, the success rate of frozen embryo transfer can be effectively improved, and the tolerance of endometrium can be significantly improved through two descending regimens, which increases the chance of blastocyst implantation. We found that the endometrial microenvironment was significantly improved after two descending regimens for endometrial thinning caused by curettage, which promoted embryo implantation. The specific mechanism still needs to be further explored.