Bone grafting is a surgical procedure that replaces missing bone with material from patient′s own body, an artificial, synthetic, or natural substitute. As natural bone grows, it generally replaces the graft material completely, resulting in a fully integrated region of new bone. The type of bone graft are allograft-based bone graft involves allograft bone, Factor-based bone graft are natural and recombinant growth , cell-based bone grafts, ceramic-based bone graft substitutes, polymer-based bone graft. The aim of study are to explore the influence of variations in the composition of alginate 8wt % , 10wt % , 12wt % to the characterization and the role of compacting pressure variation to the characterization of hydroxyapatite – alginate and to explore the best composition variation of alginate in which provides the best characteristics for application as a bone graft. All of the materials were mixed with a magnetic stirrer into liquid until homogeny, dried with oven with temperature of 50 °C, and then frozen for optimalizing the drying with sublimation method. The variation of Alginate composition were 8%wt, 10%wt, 12%wt, while the variation of compaction were 1 N/m2, 2 N/m2, 3 N/m2. The sample characterization used Fourrier Transform Infra Red (FTIR) test, compressive strength test, and MTT Assay test. Based on morphology assay, the pore sizes from samples with greater compaction force produces an increasingly smaller pore size. The result showed that variation of hydroxyapatite – alginate composition had effect to compressive strength value. The higher percentage composition of alginate, the greater pressure will increase the value of its compressive compaction and strength. The result of cytotoxicity test showed that nine samples were non toxic. In this research, the sample with composition 12% wt alginate and 3 N/ m2 in compaction was the best characteristic according to mechanical aspect.