Abstract: This paper conducts a detailed study on the influence of second-harmonic parasitic effects in non-collinear ultra-broadband degenerate optical parametric amplification (OPA), which is pumped by frequency-doubled Ti:sapphire lasers. We considered both walk-off compensation and non-walk-off compensation scenarios. The study reveals that, under the non-walk-off compensation method, by appropriately increasing the non-collinear angle between the pump and signal beams, the impact of second-harmonic parasitic effects on the signal’s output spectrum can be effectively reduced while ensuring broad-spectrum amplification of the signal. The evolution of the signal’s output spectrum and output flux is investigated for different pump spectral bandwidths, clarifying the requirements for the pump spectral bandwidth given a specific signal output spectral bandwidth. The research findings provide design guidelines for generating ultra-broadband, high-temporal contrast femtosecond seed based on degenerate OPA.