Abstract: The mechanical characteristics of porous tunnel construction are complex, and the selection of its construction scheme and stability evaluation are engineering difficulties. This paper takes a shallow-buried, unsymmetrically-loaded four-hole small-clear-distance tunnel in Fujian as the engineering basis. A three-dimensional mechanical model is established to analyze the deformation laws of the tunnel under four excavation sequences. On this basis, a deformation potential energy function based on the cusp catastrophe theory is constructed. By comprehensively considering deformations such as vault settlement and horizontal convergence and their development trends, the stability evaluation of the porous tunnel and the optimization of the construction scheme are completed. Combined with engineering practice, the rationality of the scheme is verified, and stability control measures are proposed. Mechanical analysis shows that when the scheme of "first excavating the two right tunnels with smaller burial depth and then excavating the two left tunnels with larger burial depth" is adopted, the invert heave, vault settlement and horizontal convergence of the tunnel are 18.70, 11.31 and 9.8 mm respectively, which are 10.09%-19.01% less than those of other schemes, far less than the specified values and the deformation development is controllable. The evaluation results of the overall stability of the tunnel under different sequences based on the cusp catastrophe theory model show that the scheme of first excavating the two right tunnels with smaller overburden thickness and then excavating the two left tunnels is a relatively optimal tunneling scheme. The overall fitting degree of the calculation results is greater than 0.95, and the prediction accuracy meets the engineering precision requirements. The results of deformation calculation and stability analysis are in good agreement with on-site monitoring and actual construction, which verifies the rationality of the calculation method, evaluation model and construction scheme. It is suggested that during construction, focus should be placed on the horizontal convergence deformation of the left vehicle tunnel, and local geotechnical bodies should be reinforced as needed to reduce the unsymmetric loading effect at the tunnel portal section and the risk of arch foot cracking. The research results provide practical guidance for on-site construction.