Channel-Loss and Channel-Insertion-Loss
Read many time about Channel-Loss and Channel-Insertion-Loss, but confused that, is that same thing or opposite?


They're usually the same thing. Someone might say "channel insertion loss" if there is a possibility they might also talk about the return loss so they need to be specific to avoid ambiguity.


  Which has +ve or -ve values in dB?


Unfortunately, usage is not consistent. Some people will give insertion loss values in positive dB and others will give it in negative dB. Using negative dB is more likely when the writer/speaker is considering the possibility there could be gain rather than loss in the channel (so that gain would be expressed as positive dB and loss as negative dB). But really this usage is so inconsistent that you must consider the context rather than assume one convention or the other.