Lysozyme is an antimicrobial compound without any acute toxicity. Therefore, lysozyme has been used in pharmaceutical and food industries. Nowadays, egg is the commercial source of lysozyme. However, human lysozyme is better and safer than egg-white lysozyme. Therefore, the production of human lysozyme is needed to meet the demand. Although human milk is an important source for human lysozyme, several approaches for the expression of recombinant human lysozyme have been reported for commercial production, such as transgenic plants, animals, and microorganisms. In this study Kluyveromyces lactis K7 and biofilm reactor with plastic composite support were used to produce human lysozyme. This study was undertaken to determine the optimal plastic composite support (PCS), growth conditions and fermentation medium composition for the human lysozyme production by K. lactis K7 in biofilm reactor with PCS. To find optimum growth parameters combination and fermentation medium composition, three factors Box-Behnken design was used. The results suggested the optimum growth conditions as 25°C without pH and aeration control and optimum medium composition as 16.3% lactose, 1.2% casamino acid, 0.8% yeast nitrogen base for human lysozyme production. Overall, the human lysozyme production by K. lactis K7 amount was increased to 173 U/ml from 110 U/ml by the application of biofilm reactor and optimization of growth conditions and fermentation medium.