There is a new invention developed by two companies, but one company applied for a patent. Does the other company still have the right to use this patent?

I think it's cooperative development. That depends on whether the right to apply for a patent and the terms of use of the patent are stipulated in the cooperation contract drawn up by the two companies at the initial stage of development, and if so, do it accordingly.

If not, according to the provisions of the Patent Law, both parties shall jointly apply for a patent (Article 8 of the Patent Law).

If it is not stipulated in the contract in fact, one of the units has applied for a patent, and the other unit may file a patent ownership dispute.