This paper presents the analysis of processing parameters in the fabrication of coir fiber recycled high density polyethylene composite through experimental data and Taguchi grey relational analysis. Three processing parameters; fiber conditions, fiber length, and fiber loading with mixed level design, having orthogonal array L32 (2**1 4**2) were employed in the preparation of polymer composite. Numerical analysis assisted by Taguchi design was conducted on the experimental multi-physicomechanical characteristics of the polymer composite for optimum processing parameters. The optimum grey relational grade was gotten to be 0.8286 and was experimentally validated with 95% confidence interval. The optimum processing parameters were discovered to be a treated fiber having 8 mm length at 30% loading. Although, other processing parameters are significant, but fiber loading is the most significant parameter. Correspondingly, the contribution of residual error on the overall multi-physicomechanical characteristics is insignificant having 2.43% of contribution.