Abstract: The development of integrated circuit (IC) shows the trend of miniaturization and integration, which makes the IC electromagnetic radiation more and more strong. It is of great significance to accurately test the IC electromagnetic radiation for the EMC design of integrated circuit. The transverse electromagnetic wave (TEM) chamber method is the most common IC radiation test method at present. This method uses a square test plate to test the IC radiation value at four angles (0°, 90°, 270°, 360°). Due to the angle effect of IC electromagnetic radiation, the IC electromagnetic radiation level can not be tested only by four angles. In this paper, the effect of angle on IC radiation is verified by using a single microstrip line based on TEM cell full-wave simulation model. The paper designs a round test board and a square test board based on the STM32 chip. TEM chamber is used to test the electromagnetic radiation of the STM32 chip at different angles and in different modes. The measurement results confirms that the test results of the round test board are greater than those of the square test board in different modes, and the maximum deviation reaches 16 dBm. Therefore, the round test plate can more accurately measure the electromagnetic radiation level of the chip.