Abstract: OBJECTIVE To prepare pidotimod-phospholipid complex and indentify the complex. METHODS The preparation method of pidotimod-phospholipid complex was established by single factor and orthogonal experimental design. The complex was analyzed by infrared spectrum(IR), differential scanning calorimetry(DSC) and X-ray diffraction(XRD). RESULTS The final reaction condition was established as follows:solvent was ethanol, the ratio of pidotimod to phospholipid was 1:1, reaction time was 1 h, temperature was 60℃, the concentration of pidotimod was 8 mg·mL^-1. Differences were showed in IR, DSC, XRD between complex and monomer. CONCLUSION The best preparation method of pidotimod-phospholipid complex is established. The results of IR, DSC, XRD suggest the formation of pidotimod-Ppospholipid complex.