'I have studied English for several years' is the present perfect tense. 'I have been studying English for several years' is the present perfect continuous. Both tenses can be used to describe actions that started in the past and continue up to the present moment. But, there can be a difference in meaning. We use the present perfect simple more to describe actions that are completed or that have a present result or for things we have done in our lives without specifying when. 'I have studied English for several years does not specifically tell us the action is continuing. It could have been completed at some point in my life. We can also use past simple to express this. 'I studied English for several years.' 'I have been studying English for several years' tells us that the action continues. Normally if the action continues and the verb is not a stative one, we prefer to use present perfect continuous.

I have been studying English for several years. = the length of time you have been studying I have studied English for several years. = the grade you have reached after studying so long; I have several years experience of learning English

The first. The second one is OK, though, but quite weird and vague. Instead of "study" in this case, people usually say "have learnt" something, meaning it's a "done" state, you completely finished some task, and that you already speak (or at least almost) perfect English.

the first,which uses Present Perfect Continuous Tense,is correct.