An all-gear continuously variable automatic transmission and speed ratio active control system includes a speed ratio active control mechanism arranged between a torque proportional distribution differential mechanism and a planetary gear mechanism. The torque proportional distribution differential mechanism includes two differential bevel gears connected to a gear ring and a sun gear of the planetary gear mechanism respectively to be used as input shafts of the planetary gear mechanism. The speed ratio active control mechanism includes an adjustment motor, an adjustment driving gear and an adjustment driven gear. The adjustment driving gear and the adjustment driven gear are in a normally engaged state. The adjustment driven gear is rigidly connected to one of differential bevel gear shafts, and the adjustment driving gear is connected to the adjustment motor, and planetary gears are engaged with the sun gear and the gear ring respectively and output power.