in order to realize real-time signal identification and processing of spatial transient light, the features and the energy of the captured target light signal are first described and quantitatively calculated. considering that the transient light signal has random occurrence, a short duration and an evident beginning and ending, a photodiode detector based spatial transient light detection and processing system is proposed and designed in this paper. this system has a large field of view and is used to realize non-imaging energy detection of random, transient and weak point target under complex background of spatial environment. weak signal extraction under strong background is difficult. in this paper, considering that the background signal changes slowly and the target signal changes quickly, filter is adopted for signal's background subtraction. a variable speed sampling is realized by the way of sampling data points with a gradually increased interval. the two dilemmas that real-time processing of large amount of data and power consumption required by the large amount of data needed to be stored are solved. the test results with self-made simulative signal demonstrate the effectiveness of the design scheme. the practical system could be operated reliably. the detection and processing of the target signal under the strong sunlight background was realized. the results indicate that the system can realize real-time detection of target signal's characteristic waveform and monitor the system working parameters. the prototype design could be used in a variety of engineering applications. © 2016 spie.