The invention relates to a method to test friction resistance at inner and outer sidewalls of pipe pile through in-situ test. The method comprises embedding a strain sensor at inner or outer sidewalls of pipe pile to measure strain variation generating on pipe pile body under the action of load; carrying out static load test with the soil plug remaining in the pipe pile to obtain the strain variation εp1j,i of the pipe pile body at the ith soil layer; taking out the soil plug remaining in the pipe pile and carrying out static load test to obtain the strain variation εp2j,i of the pipe pile body at the ith soil layer; and obtaining the friction respectively at the outer and inner sidewalls of the pipe pile at the ith soil layer according to the measured strain variation, εp1j,i and εp2j,i.