Soil available-P and available-K contents were measured and compared by two combined extracting agents and general extracting agent for 10 soil samples collected from different regions of China. The results showed that available-P determined by two combined extracting agents of M3 and ASI are greater than that by general extracting agent, and M3 method has a smaller variation but a higher accuracy. Significant correlation was found between M3 method and general method (P<0.01) with a correlation coefficient of 0.680. Available-K contents determined by M3 method was similar to that by general method, and significant correlation was existed between the two methods (P<0.01) with a correlation coefficient of 0.996. In a word, M3 combined extracting agent is an ideal digestion method in measuring soil available-P and available-K for calcareous soil.