Abstract: The paper introduces the structural composition of a new pattern and energy saving crank - slide bar beam pumping unit, and deduces the theoretical arithmetic formula on its geometry parameters, movement parameters and dynamical parameters. Taking CYJD12-4.8-73HB type as an example, the performance characteristics of the new pattern has been discussed. Compared with the conventional beam pumping unit, it can save energy at least 21% as well as provide satisfactory service, so it is a long - stoke pump unit which has a bright future.