In this paper, using a simple formula, we evaluate the conditional Fourier-Feynman transforms and the conditional convolution products of cylinder type functions, and show that the conditional Fourier-Feynman transform of the conditional convolution product is expressed as a product of the conditional Fourier-Feynman transforms. Also, we evaluate the conditional Fourier-Feynman transforms of the functions of the forms exp {∫sub o/$^{T}$ $ heta$(s,$chi$(s))ds}, exp{∫sub o/$^{T}$ $ heta$(s,$chi$(s))ds}$Phi$($chi$(T)), exp{∫sub o/$^{T}$ $ heta$(s,$chi$(s))dζ(s)}, exp{∫sub o/$^{T}$ $ heta$(s,$chi$(s))dζ(s)}$Phi$($chi$(T)) which are of interest in Feynman integration theories and quantum mechanics.ics.