The converter valve air cooler is widely used.If the operation state of the element is safe and stable,the HVDC transmission can operate stably.Therefore,an infrared monitoring method for the minimum AC voltage balance state of the converter valve air cooler based on multi source heterogeneous data fusion is proposed in this paper.The infrared sensor data is denoised in advance until there is no noise data in the data,and the infrared image of the temperature field distribution is calculated fusing with multi source heterogeneous data from multiple sources,reducing the data volume and spatial dimension,setting the corresponding threshold,and comparing it with the temperature field threshold to judge whether the voltage state is in a balanced state,realizing infrared monitoring of the minimum AC voltage balance state of the converter valve air cooler.The experimental results show that the proposed method is accurate in infrared measurement as well as good in monitoring image denoising.