The simple symmetrical triangular linear frequency modulation(STLFM) continuous wave range and range-rate detection ladar system and its limitations were analyzed. Dual-LO, dual-modulation dual-LO, dual-frequency dual-modulation dual-LO coherent ladar systems were proposed, which will enhance the simple STLFM systems dynamic range of detection range, the detection repetition frequency, and other performances of this system. The simulation and analysis of the key theory for these three systems and the detection accuracy were presented. Methods for further improving the ranging accuracy were proposed. The possibility to reduce the need of emitted power by pulse integration was simulated and analyzed. Comparison of those systems demonstrated that dual-frequency dual-modulation dual LO symmetrical triangular linear frequency modulation continuous wave range and range-rate detection ladar system has advantages of large dynamic range of ranging, high-repetition-rate of detection, effective ability of reduce the need of emitted power and so on.