Abstract: The seed test and yield estimate of wheat, barley, bare barley and rice is a very miscellaneous and toilsome work. To lighten the people of science and technology, and to raise efficiency of the work, a microcomputer-based automatic test system has been developed for seed test and yield estimate of wheat, barley, bare barley and rice. There are four components in the system. Three of them are sensors: a grain counter, a weigher and a measure for plant height and ear length. Another one is a controller and data process unit with 8301 single chip microcomputer.A photosensor is applied in grain counter in which there is a clearing fan for defective grain to be deleted. The sensor of weigher is a stain gauge. There is an optical fence with a photoimpact pickup assembly and video amplifier in the length sensor. The function of data process is in a wide range for calculation of count, sum, mean, weight for 1000-grain and theoretical yield of crop per mu etc. The results of output from measuring system are obtained by miniprinter or LED display.This paper details the principle and structure of the intelligent system for crops. The program and its block diagrams for microcomputer are also described.