Near-bit gamma resistivity imaging logging-while-drilling instrument

The invention discloses a near-bit gamma resistivity imaging logging-while-drilling instrument, and aims to solve the problems that in the prior art, the drilling rate of a horizontal well construction reservoir is low, and rapid and accurate evaluation is difficult. The logging-while-drilling instrument is connected to the lower portion of a drilling screw, directly connected with a drill bit and close to the drill bit for gamma resistivity imaging measurement, the defects that conventional logging-while-drilling is far away from the drill bit and stratum measurement is not timely are overcome, and accurate geosteering can be conducted; and an imaging measurement point is closer to the drill bit, so that the problem that current market instruments are difficult to meet production requirements in oil-gas exploration and development can be solved. Gamma imaging and resistivity imaging functions are fused and integrated on the independent drill collar pup joint, the resistivity measurement requirements of low-r