A method for immersion chilling and freezing tuna by CaCl2 with a low salt penetration amount, characterized by comprising following steps: carrying out a rapid block-cutting treatment on tuna meat under a sterile condition, and then immediately freezing the tuna blocks in CaCl2 salt water with concentrations of 25∼30% and temperatures of minus 25∼minus 40 DEG C respectively； completely immersing the tuna blocks in the salt water, directly placing a control group in a refrigerator at minus 25 DEG C, and when the central temperature of the tuna blocks achieves minus 18 DEG C, rapidly taking out the tuna blocks from the salt water, and measuring the salt penetration amount and the various quality indexes, wherein a chilling mode for the salt water is to place 400g of the CaCl2 salt water with the mass concentrations of 25.70%, 27.50%, 28.40% and 29.40% respectively in refrigerators at minus 25 DEG C, minus 30 DEG C, minus 35 DEG C and minus 40 DEG C, and chilling to setting temperatures of refrigerator, wherein the temperature fluctuation ranges of the refrigerators are +/-1 DEG C. The method disclosed by the invention increases the freezing efficiency of the tuna meat, has a low salt penetration amount, effectively ensures the quality and the taste of the tuna meat, and has a wide application prospect.
