Objective: To investigate the expression and significance of insulinoma associated protein 1 (INSM1) and SRY-related high-mobility group box 11 (SOX11) in pancreatic neuroendocrine tumor (PNET) and solid pseudopapillary neoplasm (SPN). Methods: To detect the expression of INSM1, SOX11, Syn, CgA, CD56, β-catenin, and CD99 in 56 cases of PNET, 42 cases of SPN, 16 cases of ductal adenocarcinoma (DACC) and 8 cases of acinar cell carcinoma (ACC) by immunohistochemistry. The application value of combination of INSM1 and SOX11 was compared with conventional markers (Syn, CgA, CD56, β-catenin, and CD99) in diagnosis and differential diagnosis of PNET and SPN. Results: (1) In the 56 cases of PNET, the positive signals of INSM1 were located in the tumor and islet nucleus, the positive expression rate in the tumor tissues was 91.07% (51/56), whereas the signal was absent in 42 cases of SPN, 16 cases of DACC and 8 cases of ACC, and there were significant statistical difference between PNET with SPN, DACC, and ACC respectively (P < 0.001). (2) The positive signals of SOX11 were located in the tumor nucleus, with the positive expression rate was 92.86% (39/42) in SPN, however, the positive expression rate of SOX11 was 8.93% (5/56) in PNET, which included 3 cases of G₁ and 2 cases of G₃ types of PNET, the SOX11 positive signal was absent in 16 cases of DACC, 8 cases of ACC and peritumoral nomal pancreatic tissue, and the differences were statistically significant of positive rate between SPN with PNET, DACC and ACC, respectively (P < 0.001). (3) The sensitivity of INSM1(+)/SOX11(-) immunophenotype for PNET was 85.71%, vs. CD56 (57.14%), the difference was statistically significant (P=0.001); vs. Syn (80.36%) and CgA (71.43%), the difference was no statistically significant (P>0.05). The specificity of INSM1(+)/SOX11(-) for PNET was 100.00%, vs. Syn (42.86%) and CD56 (47.62%), the difference was statistically significant (P < 0.001); vs. CgA (92.86%), the difference was no statistically significant (P>0.05). The sensitivity of INSM1(-)/SOX11(+) immunophenotype for SPN was 92.86%, vs. β-catenin (90.48%) and CD99 (85.71%), the difference was no statistically significant (P>0.05). The specificity of INSM1(-)/SOX11(+) for SPN was 96.43%, vs. CD99 (48.21%), the difference was statistically significant (P < 0.001); vs. β-catenin (100.00%), the difference was no statistically significant (P>0.05). (4) The positive expression of INSM1 and SOX11 in PNET and SOX11 were not correlated with clinicopathological parameters (age, gender, tumor size, location, grade, and metastasis) (P>0.05). Conclusion: The positive expression patterns of INSM1 and SOX11 in PNET and SPN respectively are conductive to distinguish the both tumors. The combination of both take precedence over some corresponding conventional immunohistochemical markers in terms of sensitivity and specificity.