The present teaching relates to facilitating a user-machine conversation. In one example, a query is obtained from a user. The query is directed to a first conversational bot. A reply in response to the query is obtained from the first conversational bot. A degree of validity of the reply is determined based on the reply and the query. A second conversational bot is determined based on the query and the degree of validity. The conversation is directed to the second conversational bot with the query.