In this paper， PDI prepolymers were synthesized using bio-based pentamethylene diisocyanate（PDI） and trimethylolpropane as raw materials. Then，the isocyanate（—NCO）groups of PDI prepolymers were reacted with methyl ethyl ketone oximeto synthesize blocked PDI curing agents. The blocked PDI curing agents were applied tocathodic electrophoretic coatings to investigate their application performance. The results indicated that the blocked PDI curing agents demonstrated excellent performance with thedosage of PDI，trimethylolpropane and methyl ethyl ketone oxime was 1 mol，0. 45 mol and 0. 55 mol，respectively. The emulsion prepared with the blocked PDI curing agents andaminated epoxy resin revealed good storage stability. The prepared coating could be cured at135 ℃/20 min，and the coating performance satisfied the application requirements.