When the microscopic particles was depicted by linear Schrodinger equation we find that the particles have only a wave feature, thus, a series of diffuculties and intense disputations occur in quantum mechanics. These problems excite us to have to consider the nonlinear interactions among the particles or between the particle and background field, which is really existed, but ignored completely in quantum mechanics. Thus use here the nonlinear Schrodinger equation containing the nonlinear interact ion to describe the microscopic particles. In this case the natures and features of microscopic particles are studied completely and in detail. From these investigations we obtain a lot of new results. The microscopic particles described by the nonlinear Schrodinger equation are localized due to the nonlinear interaction, have truly a wave -particle duality which are also very stable, satisfy both the classical dynamics equation and Lagrangian and Hamilton equations, obey the collision rules of classical particles and possess the invariance and conservation laws of mass, energy and momentum and angular momentum for the macroscopic particles. At the same time, the microscopic particles possess also a wave feature and can generate the reflection and the transmission phenomenon at interfaces, which but are different from both KdV solitary wave and linear wave. Farthermore, the position and momentum of the particles satisfy a minimum uncertainty relation, which represents a wave - corpuscle feature of the particles. These natures and features are completely different from those in the quantum mechanics. Thus we can affirm the theory established on the basis of nonlinear Schrodinger equation is a new quantum theory, the linear quantum mechanics is only its a especial case. The new quantum theory can not only solve difficulties and problems disputed for about a century by plenty of scientists in quantum mechanics but also promote the development of physics and enhance the knowledge and recognition levels to the essences of microscopic matter.