Compared with single- point scanning microscopy, multifocal multiphoton microscopy (MMM) can significantly improve the light energy utilization efficiency and imaging speed. Thus it has broad application prospects in life science. Unfortunately, there exists conflicts between the image quality and imaging speed in the available MMM systems. Although increasing focus number within a unit area can increase the imaging speed, too small focus distance will produce crosstalk between adjacent beamlets that will affect the longitudinal spatial resolution. High- density excitation focus array is simulated with Zemax, the distances between adjacent focus are reduced from 6 mm to 3 mm; the causes of noise in high- density multifocal multiphoton microscopic imaging system are analyzed; a square time- delaying plate based on the principle of time multiplexing technology is designed, which can generate different time delays between adjacent subpulses, therefore the crosstalk between adjacent beamlets is eliminated in high-density MMM imaging system.