A robust and pragmatic technique has been developed to design and apply a multiphase sucker-rod pump in wells with high gas-oil ratios. More specifically, the pump structure has been designed according to its working mechanisms in the presence of high gas-oil ratios and various liquid contents. Effective solutions of enforcing gas evacuation while enhancing oil production have also been made possible. In particular, a unique gas buffer is designed to include two chambers (i.e., a gas chamber and a fluid chamber) inside which are connected through the slotted liner, enforcing gas evacuation while preventing the pump from gas lock. Also, such designed gas buffer can be bypassed when the stroke is shortened, functioning as the traditional downhole pump. It has been found from field applications that average pumpingefficiency can be increased up to 16.6% by using such designed multiphase sucker-rod pumps in wells with high gas-oil ratios where conventional pumps have found their limits.