A new photonic approach for generating a triangular waveform with octupled-frequency is presented. The core principle is the frequency outupling technique based on two cascaded dual-parallel Mach-Zehnder modulators (DP-MZMs). A dual-electrode MZM (De-MZM) and a single mode fiber (SMF) are subsequently applied to manipulate the signal spectrum to satisfy the characteristics of that of a triangular waveform. By applying a 2-GHz radio frequency (RF) signal, a full-duty-cycle triangular waveform with repetition rate of 16-GHz is obtained. The high frequency multiplying factor shows great potential in generating a cost-effective waveform. Additionally, the phase imbalance of hybrid coupler and bias drift of MZM have been considered in our simulation, which further verify the feasibility and stability of our proposal.