The desert of Inner Mongolia is known as the east part of Asia-African desert, its east edge being the dividing line between Asia-African desert and Europe-Asian steppe.

The Taibai Mountain may be the northernmost distribution boundary for CBS J.

In this paper,we proved that the cubic system can not exist three separatrix cycles of the tri - curve x3 - 3xy2 - 1 = 0.

We obtain a necessary and sufficient condition for the existence of a type of quarticcurve separatrix cycles in the quadratic system.

This conclusion corrects a mistaken result(In the planar quadratic system there is not cubic algebraical saddle-nodeseparatrix-loop,in which the author asserrts that quadratic system has no the cubicalgebraical saddle-node separatrix cycle.

Under the conditions that the concrete expression of its singularities are not sloved,we discuss the bounded property of trajectories,separatrix configuration,nonexistence and existence of limit cycle.

The paper discusses the behaviour of equilibrium points of the volterra Predator prey system and the existence of separatrix cycle of the system with two positive equilibrium points.

in the thesis,by using the Computer, We approach separatrix of the classical Volterra model where k1>k2/β,k2>k1/α,and advance the general calculating way of separatrix.