The invention provides a desktop type 3D printer broken wire detection and alarm device. The broken wire detection and alarm device comprises a support used for supporting a tray, a weight measurement device used for measuring the weight of printing wires in the tray on the support in real time, an alarm device used for giving an alarm and a detection device arranged above a printer nozzle and used for detecting the length of the printing wires. The broken wire detection and alarm device realizes detection and alarm of broken wires in the printing process of the desktop type 3D printer, avoids the phenomenon of broken wires in the printing process, improves printing efficiency and product quality and ensures the excellent structure properties of printed products.