Abstract: Chemical flood numerical simulator UTCHEM (the improved version) is used to study alkali - surfactant -polymer flooding in typical five - spot pattern, and to calculate the displacement effects of injection methods with various polymer pre - flush profile correction slug, main alkali - surfactant - polymer slug, auxiliary alkali - surfactant - polymer slug and polymer post - flush protection slug. The calculation results show that alkali - surfactant - polymer system has some synergistic effects in improvement of oil displacement. Appropriate slug sizes and slug combinations and rational formulations can economically improve oil displacement effects.