The room-temperature liquid metal (RTLM), which is far from being fully exploited, is emerging as an ideal material for fabricating micro-droplets owing to its strong surface tension and easy phase control property. In order to find out a low-cost and technically simple way for quickly preparing metal particles in large-scale, here a channelless fabrication method based on stream jetting and self breaking up mechanisms of the RTLM when injected into and interact with the matching solution was proposed. Various typical factors on influencing the droplets generation behavior were experimentally investigated and clarified, such as the effects of the aperture size of the injection needle, the density, viscosity of the liquids and surfactants etc. Further, as an illustration of the flexibility of the present method, the direct construction of a three-dimensional porous metal block with foam-structures inside was also demonstrated. This study opened an extremely simple way for large scale fabrication of liquid metal micro-droplets and particles which has rather important practical values. It also suggests a highly efficient approach for visualizing and investigating the fundamental mechanisms of fluids interactions between RTLM and general solution.