Propagation characteristics including complex propagation constants and effective wave impedance of pins-loaded microstrip line under operation of the first higher-order EH1 mode are numerically de-embedded. Although numerous methods have studied the features of EH1-mode, full-wave numerical extraction of the entire propagation characteristics of the pins-loaded EH1-mode microstrip line is for the first time revealed. The algorithm is established by using three calibration standards, and then the two-port ABCD matrix of finite-cell pins-loaded microstrip line under EH1 mode is de-embedded to derive its complex propagation constants and effective wave impedance. Extensive investigations are executed by varying the pin diameters, and simple impedance transformers are then designed for verifying the extracted effective wave impedances.