Which internal and external departments of the company does the finance department deal with? What is the main content of communication with these departments?

Very many.

External:

Tax official: Pay tax.

Bank: everything, interest, wealth management products, card opening, foreign exchange and so on.

Government: What kind of funds are you applying for?

. . . . . .

Internal:

Purchasing: About all kinds of purchasing, such as price and quantity.

Warehouse: receipt and return, quantity, etc.

PMC: Production planning, shipping problems.

Nuclear material group: product consumption problem.

Customs declaration department: the situation of customs declaration account and accounting account of imported materials.

Personnel: personnel attendance.

Administration: There are too many administrative problems, such as maintenance fees, meals and so on.

Workshop: the number and efficiency of piecework employees.

Anyway, there are too many words. It is estimated that it will take thousands of words to sum it up.