With the emergence of drug resistance problems, many nitrogen-containing compounds have shown a wide range of biological activities. But so far, isothiazole derivatives have not been reported as antifungal agents. In this thesis, thirty-four novel pyrazole-amide-isothiazole compounds were designed and synthesised by using scaffold hopping theory. All of the target compounds have been confirmed by 1HNMR, 13CNMR and HRMS, the single-crystal culture of compound 7-XHU-2 was idendified. In addition, we performed gram scale-up experiments on target compounds 7-XHU-2 and 7-XHU-6. All the target compounds against five plant pathogens by mycelial growth rate method. The results showed that most of the compounds exhibited certain biological activities against Botrytis cinerea in vitro, compound 7-XHU-6 showed the best inhibitory activity against Botrytis cinerea and the inhibition rate can up to 98.27%. Scanning electron microscopic to observe the effect of mycelium action. Besides, the in vivo experiment indicated that compound 7-XHU-6 had excellent effect against Botrytis cinerea, protection efficiency up to 98.7%, therapeutic efficiency can reach up to 90.6%. In addition, molecular docking studies demonstrated that compound 7-XHU-6 has superior binding energy compared to the positive control fluopyram. This study demonstrates that 7-XHU-6 is a promising fungicidal candidate for further development