Abstract: After systematic breeding of 6 generations, a new improved lean pig line (DⅣ2) was bred by the combination use of molecular-assisted-selection and conventional breeding techniques with Chinese new lean pig line as the basic population and meat quality trait as the major trait. DⅣ2 line with good meat quality, high lean percentage, improved growth rate and large litter size was ideal new lean dam line. For gilts and boar of DⅣ2 line,the body weights at the age of 6 months were 103.50 and 97.77 kg and the days of age reaching 90 kg was 161.68 and 170.02 d with backfat thickness of 1.69 and 1.70 cm respectively. Average daily gain of sib test during fattening period was 714.23 g and the days of age reaching 90 kg was 170.02 d while the feed conversion rate was 2.80, lean percentage in the carcass was 60.23%, intramuscular fat was 3.13% and litter size of sows was 13.53 heads. For hybrids of “Large white♂×DⅣ2♀”, “Landrace♂×DⅣ2♀”, “Duroc♂×Large white♂×DⅣ2♀” and “Duroc♂×Landrace♂×DⅣ2♀”, the days of age reaching 90 kg was 145.1 to 157.6 d with feed conversion rate of 2.4 to 2.9, lean percentage of 66.4% to 68.1% and intramuscular fat of 2.75% to 3.36%. The results showed these hybrids were superior cross combinations for pig reproduction．

Key words: improved lean pig, new line (DⅣ2), intramuscular fat