Transmission tower burglary-resisting system has great significance on the safe operation of power network. In this paper, a terminal software system based on the QT development platform is designed for video monitoring which is used in the power transmission tower. The system automatically receives the image data transmitted by 3G network, it uses H.264 decoding technology, and then outputs image information. This paper presents a double block filter algorithm, which can repair visual defects caused by block effect. Implementation process of the system and core code can be reshaped. With minor modification and compilation in different platform, code can be ported to different operating systems and platforms and it can provide reference for cross platform software development. This paper solves the current problems in the power transmission tower monitoring terminal software such as poor portability, low video quality and so on.