His wives were Park Cha-jeong (박차정, who died before Kim married with Choi Dong Seon) and Choi Dong-Seon (최동선). His sons are Kim Cheol-Geon (김철건) and Kim Joong-Geon (김중건), and his daughter is Kim Hak-Bong (김학봉). His pen name is "Yaksan" (약산 若山), which means "like a mountain".
After remaining in North Korea, he was purged by Kim Il-sung in 1958. There are many accounts of Kim's death. According to one opinion, Kim committed suicide by taking cyanide.