ObjectiveTo investigate the significance of expression and correlation of pyruvate kinase M2 (PKM2) and yes association protein (YAP) in hepatocellular carcinoma (HCC) tissue, and then explore the relationship between the 2 kinds of protein. MethodsA total of 120 patients' HCC tissues and adjacent tissues were collected retrospectively, who treated in our hospital from Apr. 2010 to Oct. 2013, the expressions of PKM2 and YAP protein in these HCC tissues and adjacent tissues were detected by SP immunohistochemical method, and then analyzed the relationship between the expressions of PKM2 and YAP ptotein with the clinicopathological features of HCC. Of the 120 patients, the expressions of YAP and PKM2 protein and its mRNA in 50 cases of HCC tissues and adjacent tissues were also examined by Western blot and real-time PCR methods respectively. Results① The immunohistochemical results showed that, the positive rate of PKM2 protein and YAP protein in HCC tissues were 67.50% (81/120) and 71.67% (86/120) respectively, which were both higher than those of adjacent tissues[PKM2 protein:20.83% (25/120); YAP protein:29.17% (35/120)], P < 0.050. ② The expression of PKM2 protein was significantly positively correlated with the expression of YAP protein in HCC tissues (r=0.519, P < 0.001). ③ In HCC tissues, the expression of PKM2 protein was significantly correlated with the diameter of tumor, TNM staging, differentiation of HCC, and lever of alpha fetal protein (P < 0.050), and the expression of YAP protein was significantly correlated with the differentiation of HCC and lever of alpha fetal protein (P < 0.050). ④ Western blot results showed that, the expression levels of PKM2 protein and YAP protein in HCC tissues were 1.25± 0.11 and 1.08±0.10 respectively, which were significantly higher than those of adjacent tissues (PKM2 protein:0.38±0.01, YAP protein:0.41±0.02), P < 0.050. ⑤ Real-time PCR assays results showed that, basing the expressions of PKM2 mRNA and YAP mRNA in adjacent tissues (both as 1), expressions of PKM2 mRNA and YAP mRNA in HCC tissues were 11.38±0.35 and 19.96±0.48 respectively, which were both higher than those of adjacent tissues (P < 0.050). ConclusionPKM2 and YAP protein were related to the initiation of HCC, and they were also closely correlated with the differentiation and prognosis of HCC.