Abstract: The system complexity of sports techniques hasn't been fully interpreted so far. To better understand the issue, this paper applies the system complexity theory to analyze the components, their relationship (structure), and functions. This study suggests that tennis technique system is an open system which includes the principal subsystem, technique subsystem, environment subsystem, and time-space subsystem. These subsystems are interconnected as a whole through its internal relations, showing the complex features of uncertainty, non-linearity, self-organization, and cluster. The perception of hitting the ball, as a comprehensive key factor in the tennis technique system, plays a profound role in the generation, operation and optimization of the technique system through the positive feedback amplification mechanism, nonlinear interaction, and self-organization mechanism. The research on the perception of hitting the ball provides a new perspective for thorough understanding of sports technique system complexity and the internal mechanism and rules.

Key words: sports technique system, tennis, complexity, perception of hitting the ball