A multi-cyclone separating apparatus of vacuum cleaner comprises a upstream cyclone forming upstream separating chamber inside, downstream cyclones at least one of which forming downstream separating chamber inside, the upper part of the upstream cyclone chamber is connected with an air inlet passage, said upstream cyclone has a upstream guide air intake inside, the downstream cyclone has a downstream air intake and the downstream cyclone has a downstream guide outlet inside, an air passage is formed between upstream guide air intake and downstream guide outlet which connected with the two. The multi-cyclone separating apparatus also comprises an outer cyclone body, the upstream cyclone is located inside of the outer cyclone body and the entrance of air inlet passage is located at the outer cyclone body or extend to the outside of the outer cyclone body.