The purpose of this study was to detect the serum PTK7 level of patients with acute lymphocytic leukemia, and to reveal its clinical value for diagnosis of diseases. A total of 136 patients diagnosed as acute lymphocytic leukemia from May 2012 to April 2014 in our hospital were enroled in this study and were divided into the L1 group (n = 42), L2 (n = 45) and L3 group (n = 49) according cytomorphology, and 48 normal children were selected as control group. Fluorescence quantitative PCR was used to detect mRNA level of PTK7 in peripheral blood mononuclear cells, and Western blot was used to detect PTK7 protein expression. The results showed that the PTK7 mRNA level in L1 group was significantly higher than that in normal group (P = 0.000) . The PTK7 mRNA level in L2 group was significantly higher than that in the L1 group (P = 0.000). The PTK7 mRNA level in L3 group and L2 group had not significantly different between each other (P = 0.123). Serum PTK7 protein level in L1 group was very significantly higher than that in normal group (P = 0.000) . The serum PTK7 protein level in L2 group were very significantly higher than that in the L1 group (P = 0.003) and serum PTK7 protein level in L3 and L2 group had no significance difference (P = 0.312) . It is concluded that the expression level of serum PTK7 protein has a potential clinical value for the diagnosis of acute lymphocytic leukemia, but without specificity for ALL subsets.