This thesis studies passive harmonic filter design in high voltage systems based on normal conditions. Results lead to development of a computer program to design harmonic filter such as single-tuned, second order high-pass, third order high-pass, c-type high-pass filters. The design of capacitor bank such as externally fused, internally fused and fuseless are also considered. Moreover, the developed program can perform load flow, harmonic flow, frequency scan and voltage waveforms at various buses. Results from capacitor bank design can simplify and speed up passive harmonic filter design in high voltage systems. Proper measures can be implemented to mitigate harmonic problems.