The connection unit is the most common part of the change in the reproduction unit, and the reproduction unit does not need to emphasize the contradiction between the main and the sub-sections as in the presentation unit, but balances the unstable state of the non-main tone for a long time. Compensation, this unstable state happens to start from the connection portion in the presentation portion, and the connection portion in the reproduction portion requires almost no modification. This change is unique in Beethoven’s piano sonata style, with different techniques, reflecting Beethoven’s skilled writing skills and personal style.

Abstract
Introduction
1. The separate connection is no longer used in the reproduction unit
2. The structure of the connection part in the reproduction unit hasbeen adjusted.
3. The material of the connecting portion in the reproducing portionchanges.
4. The harmony phenomenon of the connection portion in thereproduction unit is complicated
5. The tonality of the connection in the reproduction unit changes.
References

• Liu wei ming(Hunan City University,Hunan.China, Dongbang Culture University,South Korean)