This study analyzed the stability of predator-prey ecosystem (including the sensitivity of the initial value and coefficient) via the original Lotka-Volterra model and three improved models. The first improved model considered the impact of hunting and internal competition on the ecosystem, the second introduced the second prey to the original model, while the third added the second-type predator and the second-type prey to the original system. The performed numerical simulation of the original and three improved models proved instability of the ecosystem represented by the original Lotka-Volterra model and the stability of those represented by all three improved models.