Accurate testing of alternative fuel injection characteristics for direct-injection internal combustion engines is crucial for optimizing combustion systems and reducing emissions within the framework of carbon peaking and carbon neutrality goals. Analysis of current test methods for liquid fuels, gaseous fuels, and dual-fuel coupled injection reveals existing limitations and suggests improvement pathways.For liquid fuels, optimized test chamber structures and multi-sensor strategies enhance the measurement accuracy and signal-to-noise ratio of multiple injection events. However, pressure wave reflections in the long tube method still require correction. In gaseous fuel testing, methods like momentum flux, long tube, and pressure-time measurement capture transient injection behavior. Yet, high-pressure gas compressibility and pressure wave reflections limit injection quantity measurement accuracy.Traditional single methods struggle with dual-fuel coupled injection due to differing fuel properties and coupled hydraulic interactions. Combined testing modes achieve breakthroughs through synchronous, co-located measurement. Current research reveals persistent challenges in dynamic response, adaptability to complex operating conditions, and signal processing. Future work must integrate numerical simulation with high-precision sensing technology to support the development of highly efficient, clean combustion systems.