Poincare dispersed-dot plot is an important nonlinear dynamics method that can effectively describe the attractor shape. Yet studies in the past generally processed the plot in a graphic mode without further discussion on the quantitative indices. That was not suited for clinical application and studies. So, based on the shape of Poincare dispersed-dot plot, we propose a group of quantitative parameters of Poincare dispersed-dot plot: plot square(SQ), long axis (LA), short axis(SA), and angle related to long-axis and short-axis(ALS). According to the characters of the heart rate Poincare dispersed-dot plot, we have posed the 'tortoise crawling and counting' algorithm to get these four quantitative parameters. We have tested these four quantitative parameters with clinical and animal experiment data. The results demonstrate that these four parameters are of certain specificity to heart diseases, indicating that these parameters might be useful for clinical diagnosis.