The present invention discloses a downhole cylindrical linear motor transmission and oil and gas exploitation system, and belonging to the oil and gas exploitation technology field. The downhole cylindrical linear motor transmission comprises an outer barrel, a driving rack, a driven rack, a rail bearing, a bearing shaft, a driving gear, two driven gears and a gear shaft. The diameter of the driving gear is larger than the diameter of each driven gear, the driving rack is engaged with the driving gear, and the driven rack is engaged with the driven gears; the driving rack is connected with the rotor end of the downhole cylindrical linear motor, and the driven rack is connected with the plunger of a downhole pump body to increase the force transmitted by the driving rack to the downhole cylindrical linear motor through the transmission of the gear set so as to increase the output force of the downhole cylindrical linear motor in the condition without increasing the power of the downhole cylindrical linear motor.