The invention discloses an application of a nanogold-carbon nano tube-chitosan composite membrane cell sensor to detection of toxicity of food-borne pathogenic bacteria and belongs to the technical field of detection of toxicity of Gram-negative pathogenic bacteria. According to the application, a magnetic glassy carbon electrode is modified with nanogold-carbon nano tube-chitosan with a self-assembly method, mouse macrophages Ana-1 endocytosing magnetic nanoparticles are taken as a sensing medium and directly adsorbed by the modified electrode, and the sensor is constructed; finally, the sensor is applied to lipopolysaccharide toxicity evaluation of the Gram-negative bacteria, has the obvious toxic effect change with the lipopolysaccharide concentration in the concentration range of 1-5 mu g mL<-1>, and has the detection limit of 0.3 mu g mL<-1>. The toxicity of the Gram-negative bacteria is detected with the method efficiently, conveniently and quickly, defects of traditional toxicity detection methods of the pathogenic bacteria are overcome, and the obtained sensor is simple to prepare, convenient to operate and low in cost and has the bright application prospect in the aspect of evaluation of the toxicity of the pathogenic bacteria.