为了寻找简单的多组全动型变焦系统的解算方法及降低全动型变焦距系统设计时对经验的过分依赖，提出了一种全新的方法来计算系统组元的光焦度分配。以组元之间的间隔为初始量，把组元的运动形式作为自由量，通过计算公式求出满足间隔要求的光焦度分配和组元运动形式。该方法在一定程度上降低了变焦系统光焦度分配的难度，更重要的是，为探寻新的变焦运动方式提供了一种新的思路。在得到系统的光焦度分配之后又推导出一种求解系统组元移动曲线的简单方法。为了验证该方法的可行性，设计了一个四组式全动型变焦系统。所设计系统优化后的光焦度分配值和计算的结果都很接近，并且得到了组元的移动曲线，从而验证了该方法的正确性。

In order to get the simple computational formula for all movable zoom lens and reduce excessive dependence on designing experience of zoom lens, a new way to calculate optical-power distribution of zoom system is proposed. Taking the group spacing as initial parameter and the actions of components as independent variables, the corresponding optical-power distribution and actions of components which satisfy the constraint of group space is get. This method reduces the difficulty of optical-power distribution and it is more important it provides us with another way to find the new varifocal moving mode. After getting the power distribution, we also deduce a simple way to obtain actions of each component. In order to prove the feasibility of this method, a four movable component zoom lens is demonstrated and the calculation result agrees well with the optimized result.