Selection and parameter design of MIMO radar waveform directly determine the key radar performance such as detection range, system resolution and accuracy, and potential ability of anti-interference. Based on the fuzzy function theory and MIMO formation parameters, this paper analyzes the time-frequency-space 3D fuzzy function of DDMA-LFM waveform set, and analyzes the relationship between the waveform set and array flow pattern and radar detection performance in range-velocity-azimuth three dimensions. Combing the transmitted waveform set and the radar array flow pattern to derive the three-dimensional time delay-Doppler frequency-space orientation MIMO ambiguity function. Through formula analysis and simulation results, it is concluded that the continuity of the waveform is ensured and the design process is simplified.. In the process of designing the orthogonal DDMA-LFM waveform parameters of the Multiple-Input Multiple-Output (MIMO) radar system, there is no need to optimize the coding. What’s more, the range (time delay) resolution performance and the spatial orientation can be Separated independently, and the Doppler frequency and the spatial orientation are mutually coupled but the radar resolution performance is not affected within the effective Doppler spectral width, meanwhile the interaction between the waveform set and the array can improve the angular resolution of certain orientations to a certain extent about 5°.