This paper presents the use of finite Matrices to encrypt messages encoded using ASCII system, dependent on the method (Hill cipher) 1929 by: 1. Using finite Matrices to divide the text into partial Matrices. 2. Depending on encoding ASCII (ASCII Coding). 3. Using the matrices A,X,B have special conditions to make Hill function ( f(X)=(A.X+B)mod(n)) able to encrypt the text P that corresponding in the matrix. This matrix contains partial Matrices to get encryption messages with different keys to make it difficult to break, and save the security of information in the texts. 4. Method can be applied on the computer to give quick and great results.