Objective To explore the impacts of different estrogen receptor α (ERα) isoforms on biological effects of endometrial cancer (EC) and the prognosis of EC patients. Methods A retrospective study was carried out for 116 endometrial cancer patients and an analysis of relationship between the ERα isoform expression pattern of EC tissue and the clinicopathological data and prognosis was performed. Patients' RNAs were extracted from paraffin sections and Real-Time PCR was used to analyze the gene's expression level. Results ERα expression level was related to the tumor differentiation grade (rs=-0.214, Spearman's test), lymphonode metastases (rs=-0.186, Spearman's test), and FIGO stage (rs=-0.221, Spearman's test). ERα exon 7 skipping isoform (Δ7) was the most commonly detected isoform.  Δ7 was related to the tumor differentiation and FIGO stage and its high expression level was found relating to the preferred surviva (diseasespecific survival P=0.026, disease-progression free survival P=0.038). Conclusion ERαΔ7 is an independent prognosis factor of endometrial cancer and its expression level affects the prognosis of endometrial cancer patients.