The present invention discloses a test system and a test method for detecting the cement content of cement stirring pile body in real time at a construction site. The test system specifically includes a cement slurry density measuring apparatus and a cement admixing amount calculating apparatus. The method includes measuring the density of the cement slurry in the cement slurry tank, measuring the cement soil density and inputting measured values to calculate the cement content. The cement slurry density and the cement soil density can be detected in real time, so that the admixing amount of the cement can be detected in real time during the foundation reinforcing process of the underground engineering, convenience and rapidness are achieved, the time period is short, a supervision effect is good, and cheating on workmanship and materials can be effectively avoided.