介绍了载于FY-3A气象卫星用来监测太阳辐照度变化的太阳辐射监测仪(SIM)的工作原理，描述了该监测仪的系统组成和工作模式。SIM由3台相同的太阳辐照绝对辐射计(SIAR)按一定角度排列构成测量三通道，3个通道可单独或同时进行测量，对获得的数据进行对比、查验和校正。分别介绍了太阳辐射监测仪的3种工作模式，即通道自测模式、太阳辐射测量模式和冷空间测量模式，在此基础上对其执行的在轨运行任务进行了分析说明。讨论了程控设计要点与实现，给出了SIM采用各测量模式获得的遥感数据。FY-3A太阳辐射监测仪从2008年6月开始执行在轨测量，得到的实验结果表明，设计的测量模式合理，运控参数有效，全部软件功能均已实现，测量得到的太阳辐照度与同国际同期卫星SORCE/TIM的测量数据在0.2%以内相符。

The working principle of the Solar Irradiance Monitor (SIM) boarded on FY-3A meteorological satellite for monitoring solar irradiance was introduced and its system construction and working modes were described. The SIM was composed of three solar irradiance absolute radiometers (SIAR). The three SIARs were arranged with a certain angle to form three measuring channels to survey the solar irradiance simultaneously or independently and to compare, prove and correct the data obtained. Three kinds of working modes of the SIM were described, and then the tasks of SIM on-orbit was analyzed in detail. Furthermore, the software design and implementation of SIM were introduced and remote sensing data obtained on orbit with different measurement modes were given. The SIM on FY-3A has been worked normally on orbit from June 2008, and experimental results demonstrate that the measurement modes are reasonable, parameters for control and running are validity, and the task of monitoring solar irradiance are supported by the software functions designed. Moreover, the solar irradiance measured by the SIM is well coincident with that simultaneously measured by SORCE/TIM in 0.2%.