The invention relates to a fabric antibacterial finishing agent. The fabric antibacterial finishing agent is prepared from the following components in parts by weight: 5 to 8 parts of alkyl glycoside, 8 to 12 parts of chitosan, 2 to 3 parts of sodium alginate, 3 to 5 parts of citronellal essential oil, 3 to 6 parts of polyethylene glycol and 50 to 70 parts of water. According to the fabric antibacterial finishing agent, a finishing agent which is used for fabric finishing and has broad-spectrum antibacterial activity is obtained by selecting an appropriate rare earth element-lanthanum and matching a specific sterilizing agent; fabric is finished by adopting the fabric antibacterial finishing agent disclosed by the invention, the antibacterial property of the finished fabric on staphylococcus aureus and escherichia coli is 95 percent or above, and the antibacterial property of the finished fabric is still 90 percent or above after the finished fabric is washed for 50 times.