This research was carried out to investigate the expression of miR-34a, miR-34b and p-PI3K, p-AKT, and mTOR proteins in colorectal adenocarcinoma and corresponding distal cutaneous normal mucosal tissues and their relationship with the clinicopathological parameters of colorectal adenocarcinoma as well as the correlation between miR-34a, miR-34b and PI3K/AKT/mTOR signaling pathway. The expression of p-PI3K, p-AKT, and mTOR proteins in 67 colorectal adenocarcinomas and the corresponding distal cut-off normal mucosa were assayed by immunohistochemistry. Their relationship with clinicopathological parameters and the correlation of the three proteins were evaluated. The expression of miR-34a and miR-34b in colorectal adenocarcinoma and the corresponding distal cutaneous normal mucosa was detected by applying real-time quantitative PCR. The correlation between colorectal adenocarcinoma tissue miR-34a, miR-34b and p-PI3K, p-AKT, and mTOR proteins, respectively, was analyzed. Results showed that the expression of p-PI3K, p-AKT and mTOR proteins in colorectal adenocarcinoma tissues was higher than that in the corresponding distal cutaneous normal mucosa (P=0.000), and there was a positive correlation between the expression of the three proteins in colorectal adenocarcinoma tissues. The expression of p-PI3K and p-AKT protein in colorectal adenocarcinoma tissues were correlated with tumor size, differentiation degree, infiltration degree, lymph node metastasis and TNM stage (P<0.05). The expression of mTOR protein was related to tumor size and differentiation degree (P<0.05). The relative expression of miR-34a and miR-34b in colorectal adenocarcinoma tissues was less than that in the corresponding distal cutaneous normal mucosa (P<0.05), and the expression of miR-34a and miR-34b was positively correlated. The expression of miR-34a and miR-34b in colorectal adenocarcinoma tissues was negatively correlated with the expression of p-PI3K, p-AKT and mTOR proteins. In conclusion, the PI3K/AKT/mTOR signaling pathway may promote colorectal adenocarcinoma and differentially participate in differentiation, infiltration and lymph node metastasis. Also, miR-34a and miR-34b may inhibit colorectal adenocarcinoma. Importantly, miR-34a and miR-34b may affect the development and progression of colorectal adenocarcinoma by regulating PI3K/AKT/mTOR signaling pathway.