Can I enter Germany for multiple times on a D visa?

Yes, you can. German D visa allows multiple entry and exit.

Explain the reason:

German visa (D visa) refers to:

Holders are allowed to stay in Germany or stay for more than 90 days. German visas also allow holders to transit in other Schengen countries. For some German visa holders, such as spouses of German citizens, workers, students and tourists, they will also be allowed to travel freely in Schengen.

? In China, it is a common practice for international students to obtain a D visa. Students with this visa need to apply for a residence permit at the local institution in charge of foreigners' residence within the validity period of the visa after arriving in the destination country. With Schengen residence, you can go to other Schengen countries. Note: you can't travel to other Schengen countries with a D-sign. Even without border control, you still enter the country illegally.