After a Hong Kong company changes its shareholders, can it check the information of its previous shareholders?

Yes, the company registry has complete information for inquiry, including information such as shareholder change. You can make public inquiries or entrust a Hong Kong lawyer to make inquiries on your behalf. If it is to be used in China, it is recommended to be certified by a notary public in China. In previous years, the cost of full-set search (including certification) was around HK$ 3,000. If you just search, it seems to be free or very cheap.