The application of InGaAs focal plane arrays (FPAs) requires high density and small pixel pitch. However, as the pixel pitch decreases, the pixel coupling becomes stronger. By fabricating 5 μm pitch InGaAs arrays with different scales, the pixel coupling effects in high-density InGaAs arrays were studied. Innovatively, matrix equations were introduced to describe the contributions of dark current from each part, and a mathematical model of pixel coupling was constructed, and the contributions of the dark current resulting from the coupling effects were quantitatively analyzed. The results indicated that at a bias voltage of -0.1 V, a reverse-biased pixels in the array can reduce the dark current of adjacent reverse-biased pixels by 21.39% of the pixel's initial dark current. In contrast, zero-biased pixels can increase the dark current of adjacent reverse-biased pixels by 219.42%. Based on this high-density focal plane pixel coupling model, the impact rules of pixel coupling on dark current have been summarized, providing new insights for dark current research in high-density InGaAs focal plane arrays.