This paper describes new proposed algorithms for constructing the transfer function of nth order Butterworth LPF using the idea of the cascade combination of active filters. Computer-aided design is used with new algorithms to achieve the procedure of constructing the transfer function and give the practical results of the nth order Butterworth active LPF. C++ program is used for designing procedure by linear programming. The proposed algorithms are very fast, flexible, and exact. The program allows users to design different frequency, components, and order of Butterworth active LPF with high flexibility.