Based on a spintronic terahertz source employing a heterostructure of ferromagnetic metal Ni₈₀Fe₂₀ and non-magneticmetal Pt, the amplitude of terahertz waves can be modulated by applying currents with different current densities. The spintronic terahertz source is connected to a Printed Circuit Board(PCB) via wire bonding. By applying various magnitudes of current through a current source, the electromagnetic signals radiated from the spintronic terahertz source are collected within a Terahertz Time-Domain Spectroscopy(THz-TDS) system. Since current application generates Joule heating in the spintronic terahertz source, heat accumulation leads to temperature rise, which reduces the saturation magnetization of the ferromagnetic material. The terahertz amplitude, influenced by the saturation magnetization of the ferromagnetic layer, decreases with increasing applied current, thereby achieving both signal generation and electrical modulation of the spintronic terahertz source. A modulation depth of approximately 59% is realized across the frequency range of 0.1~2.8 THz. Theoretical derivation reveals that the terahertz emission amplitude is linearly proportional to the cube of the applied current density, which is confirmed by curve fitting of experimental data. This electrical modulation method facilitates the integrated development of spintronic terahertz sources, enriches existing control approaches, and provides a novel pathway for understanding the operational mechanism of spintronic terahertz sources.