The optimization process of Remora Optimization Algorithm （ROA） includes three modes： attaching to host， empirical attack and host foraging， and the exploration ability and exploitation ability of this algorithm are relatively strong. However， because the original algorithm switches the host through empirical attack， it will lead to the poor balance between exploration and exploitation， slow convergence and being easy to fall into local optimum. Aiming at the above problems， a Modified ROA （MROA） based on chaotic host switching mechanism was proposed. Firstly， a new host switching mechanism was designed to better balance the abilities of exploration and exploitation. Then， in order to diversify the initial hosts of remora， Tent chaotic mapping was introduced for population initialization to further optimize the performance of the algorithm. Finally， MROA was compared with six algorithms such as the original ROA and Reptile Search Algorithm （RSA） in the CEC2020 test functions. Through the analysis of the experimental results， it can be seen that the best fitness value， average fitness value and fitness value standard deviation obtained by MROA are better than those obtained by ROA， RSA， Whale Optimization Algorithm （WOA）， Harris Hawks Optimization （HHO） algorithm， Sperm Swarm Optimization （SSO） algorithm， Sine Cosine Algorithm （SCA）， and Sooty Tern Optimization Algorithm （STOA） by 28%， 33%， and 12% averagely and respectively. The test results based on CEC2020 show that MROA has good optimization ability， convergence ability and robustness. At the same time， the effectiveness of MROA in engineering problems was further verified by solving the design problems of welded beam and multi-plate clutch brake.