The typical final state for a tbar H associated production where the Higgs decays into a pair of b quark is a high multi-jet event. The expected jet number for one (two) semi-leptonic top decay or fully hadronic top decay is respectively 6(4) and 8. All the proposed techniques to optimize signal selection with respect to background suppression use mainly lepton tag, jet energy cut and b-tagging. The choice of the jet algorithm is therefore crucial to improve the chance to detect a light Higgs boson in the top-associated H production. Many previous studies both with fast and full simulated events show that different jet algorithms give different results in the selection procedure. To fully investigate the effect of different jet algorithm is however mandatory to use calibrated jet both from detector effects and jet formation physical model point of view. The different jet finders and Monte-Carlo jet calibration parameters are studied relatively to the best performance for the tbar H channel observability. The set of algorithm chosen is iterative cone algorithm with cone size going from 0.30 up to 0.50 (with 0.05 step) and inclusive K perp~ algorithm with r=0.4.Different calibration parameters as a function of eta, E_T and jet flavor have been calculated. Finally an example of different jet to parton pairing efficiency for the fully hadronic ttbar H decay is computed
