In the internal purchase group on JD.com, you can find a reliable group through the following channels:

1. Official channels: You can find certified internal purchase groups through the channels provided by JD.com. JD.com may promote and recommend credible internal purchase groups on its official WeChat public account, official Weibo and other platforms. Such groups usually have certain audit and management mechanisms to ensure the authenticity of the goods and the quality of the service.

2. Word-of-mouth recommendation: You can ask your friends, family or colleagues around you to see if there are any reliable internal purchase groups they have joined. Word-of-mouth recommendations are usually more reliable because they have had personal experience.

3. Social media and forums: There are some discussion groups about internal purchases on JD.com on social media platforms or related forums. You can search for relevant keywords to find some groups with high activity, large number of members and good reputation. Before joining, you can first understand the rules of the group, the reputation of the members and the transaction situation.

No matter which method you choose, you need to be vigilant and pay attention to the security of verifying information and conducting transactions. When joining an in-app purchase group and conducting transactions, it is recommended to choose carefully, understand the rules and how the group works, and avoid encountering unreliable or risky groups.