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， 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.