An experimental design was constructed to measure the temperature field on an external thermal insulation composite system（ETICS） with colorful steel plate（CSP）. Three rigs of ETICS with CSP finish of various insulation materials（foam glass, rigid polyurethane foam and foam concrete） were tested inside a weathering test chamber. The thermal fields of the rigs were measured during the heat rain cycles. Based on the measured temperature data, distribution of temperature on the walls structural layer，time lag and decrement factor were explored. The results show that the temperatures of the CSP finish and the outer face of the insulation layer tend to change in accordance with the air temperature of the chamber; the temperatures of CSP finish change quickly and intensely（especially near the window） while the temperatures of the bonding layer change slowly. Among the three insulation materials, the rigid polyurethane foam is the most efficient in energy conservation. In all three ETICSs, each layer tends to cause time lag and decrease in the transmission of thermal waves from the exterior to interior parts, being more obvious in the insulation layer.