Transfer impedance of solid shielded enclosure is modeled by parameter estimated method. Comparison shows that the estimated result fits well with traditional analytical solution. Induced currents of electromagnetic pulse (EMP) in shielded enclosure and inner conductor are calculated by introducing the estimated transfer impedance to transmission line equations in time domain. By calculated currents, shielding effectiveness (SE) of the solid shielded enclosure can be estimated and the expression of SE is fitted by exponential fitting. This work provides an effective method to estimate SE and choose shielded enclosure in actual project.