In this work quasi-bound level energies, energy dependence of the transmission coefficients and negative differential resistance properties are studied in double and multi-barrier structures. Various barrier types such as rectangular, trapezoidal and triangular are chosen. In order to compare calculation results, maximum of the barrier height and base of the barrier width are kept constant. Only changes due to barrier shape and well region width are investigated. Mini-band formation in multi-barrier structures with different barrier shapes are compared for several well widths in energy scale. In addition, properties of the resonant tunneling peak shapes, I-V characteristics, peak-to-valley current ratios in negative differential resistance regions are compared for rectangular, trapezoidal, triangular barrier types for both double and multi-barrier structures.