Abstract: The Osteopontin cDNA in size of 909 bp was cloned by RTPCR and analyzed by bioinformatics. The results showed that Asp, Glu and Ser occupied the highest proportion and the special sequence ArgGlyAsp (RGD) existed in OPN primary structure, α helix occupied the higher proportion in secondary structure and hydrophile was better, OPN signature existed in the first homologous region and the mutual conservative sequence was ［KQ］x［TA］x(2)［GA］SSEEK in OPN secondary structure. Two phylogentic trees constructed based on OPN protein sequence showed that the relationship between pig and cow was the closest, but distant from chicken. OPN mRNA was expressed in many tissues of pig: higher in stomach, kidney, lung, small intestine and ovary, lower in heart, spleen and large intestine. The protein size was different in different tissues: 70 ku, 70 and 45 ku, 70, 45 and 24 ku.