Located between the microwave millimeter and infrared frequency bands, terahertz waves possessing both electronic and photonic properties have been extensively researched and utilized in various fields such as high-speed communication, radar imaging, atmospheric remote sensing, and astronomical observation. The terahertz frequency source is a crucial component of the terahertz system, playing a vital role in its overall performance. In recent decades, solid-state terahertz frequency sources based on semiconductor devices have gained widespread attention due to their compactness, high degree of integration, and low cost of production at scale. Among nonlinear semiconductors, the Schottky diode offers several advantages, including a high cutoff frequency, low power consumption, and good noise performance. These features make it the preferred choice for low-cost and high-performance frequency sources in various terahertz applications. As a result, Schottky diode-based multiplied sources have become an important part of solid-state terahertz frequency sources. This review introduces the development of the Schottky diode and the latest research progress on solid-state terahertz frequency multipliers based on Schottky diodes. Additionally, building upon the current situation, this paper also explores the potential future advancements in terahertz frequency sources.