The invention discloses a control method for a multi-split air conditioner outdoor unit electronic expansion valves during heating. The method comprises the steps that 1, the average target opening A1 of all electronic expansion valves is calculated out; 2, whether the average target opening A1 is smaller than Amax or not is judged, if yes, the third steps is executed, and if not, the fourth step is executed; 3, half of the electronic expansion valves are switched off, the number of steps of the other half of the electronic expansion valves is adjusted to be 2A1, the switched-on electronic expansion valves are monitored in real time, and if the requirement that the openings of the switched-on electronic expansion valves are larger than the disengaging value At is met, all the electronic expansion valves are switched on with the same number of steps; 4, the number of the steps of all the electronic expansion valves are adjusted to be A1 for operation; 5, after operation is conducted for 20-40 seconds, whether the average target opening of all the electronic expansion valves at the moment is smaller than Amax or not is judged, and if yes, the third step is executed again. According to the method, it can be guaranteed that the openings of the outdoor unit electronic expansion valves are kept within the reasonable range.