The invention discloses a test device and method for interfacial mechanical properties of a pile and foundation soil. The device is characterized in that two vertical counterforce beams are arranged on two sides of a lower support device, and a horizontal counter force beam is fixedly connected between the two vertical counter force beams; an opening is formed in the upper end of a test box body,a test soil body is arranged in the test box body, the lower end of the test box body is fixedly connected to the upper portion of the lower support device, a bearing steel plate is arranged on the upper portion of the test box body, and circular holes are formed in the two side walls of the test box body; a test pile model penetrates through the test box body through the pair of circular holes; ahorizontal pushing device and a displacement sensor are oppositely mounted on the outer sides of the two ends of the test pile model; the telescopic end of the horizontal pushing device is fixedly connected with one end of the test pile model; and a vertical loading device is fixedly connected with the horizontal counter force beam, and the telescopic end of the vertical loading device is fixedlyconnected with the center of the upper end of the bearing steel plate. The method comprises the following steps of assembling, applying a vertical load by a vertical loading mechanism, applying a horizontal load by the horizontal pushing mechanism and recording parameters and drawing a characteristic curve. According to the test device and method for the interfacial mechanical properties of the pile and the foundation soil, the friction characteristics between pile bodies and soil bodies with different soil properties under different vertical load conditions can be studied.