This paper deals with thoe self-bonding poplar wood dry-processing MDF and its bonding mechanisms of fibers treated with active agents, such as NaOH, HNO,3, and H,2,O,2,. Through mathematical analysis of the experiment, the best results have been gained between the variable ranges of parameters.The optimization conditions are as follows: 1) The ratio of active agent absolute dried weight to the oven dried weight of fibers: 2% for using NaOH as activator. 2) The ratio of gap-filling material absolute dried weight to that of fibers. 10-12%. 3)Temperature of hotpress: 220℃. 4) Time of hot press: 18 min. 5) The moisture content of dried. fibers: 7-7.5%. The optimization strengths are as follows: MOR: 25（MPa）, IB: 0.46 （MPa）, MOE: 3680 （MPa）, LS: 0.72%, THS. 9.65%, MC: 3.96%, Density: 0.78g/era,3,.The bonding mechanisms,of MDF activated with NaOH are: 1) Theeompetition reaction between the degradation and condensation reaction of lignin and gap-filling materials. 2) Bonding between semicellulose and lignin （LCC）. 3) Hydrogen bond force and the combination of free radicals.