Before you start panicking about meeting your boyfriend's parents, it's important to make sure that you're both on the same page about the significance of the meeting. If you've already had "the talk" about the direction and seriousness of your relationship and exchanged the L-word, it could be a sign that your boyfriend is ready to make a serious commitment. Maybe he's even thinking about popping the question.
Or, maybe there's little to no significance at all, and he's not thinking any further than just a basic, get-to-know-you sort of gathering. If that's OK with you, then you can relax a little bit. But if your relationship isn't what you consider all that serious yet, you might not be ready to meet the parents. Then again, you might learn a lot of interesting information about him from his family.
Also, consider what kind of meeting that your boyfriend's suggesting. Is it a casual barbecue with just his parents or a formal Christmas dinner with dozens of relatives? The latter might be a bit overwhelming. Tell your boyfriend how you feel, no matter what, even if it's difficult. It'll save you potential discomfort and awkwardness later on.