The utility model relates to a thin film separation type concrete air content measurement instrument which comprises a tank body, an upper cover, a soft thin film, a water filling valve, an air chamber and a pressure meter, wherein the tank body and the upper cover are fastened by adopting fasteners; the soft thin film is arranged between the tank body and the upper cover; a containing space for containing the soft thin film is formed in the upper cover; the water filling valve is arranged on the upper cover; the air chamber is arranged on the top of the upper cover; the pressure meter is connected to the air chamber. According to the concrete air content measurement instrument, the deformation of a slurry body can be adapted by virtue of good deformability of the soft thin film, the concrete slurry body can be effectively separated from added water and the upper cover under the circumstance that the air content is normally measured, the loss of bubbles in the concrete slurry body during water filling is avoided, a measurement result is relatively accurate, a using process is relatively clean, easy and convenient, the valve is not easily worn, a relatively dirty concrete mixing field environment can be adapted, the wear and faults of the measurement instrument are reduced, and the service life of the measurement instrument is greatly prolonged.