Nano silver is widely used in conductive lines for its advantages, nano size, low melt temperature and excellent conductivity. In general, nano silver of less than 50 nm need be sintered at 200 centigrade in order to acquire conductivity, but it limits the choice of the substrates, only high temperature resistant substrate can be used, for example, PI film and glass. In order to acquire flexible tracks with excellent conductivity at room temperature on paper and PET, nano silver emulsion of 2 percent silver content was prepared through liquid phase chemical reduction, and then the concentration of silver was improved to 17 percent by centrifuging at high speed. And the emulsion was adjusted to meet the demand of inkjet printing, such as surface tension, and viscosity, pH value, then was jetted onto photo paper and PET film. High conductivity was acquired after treated by 830 nm infrared laser, and the sheet resistance is less than 2 omega/(see symbol). After aging test, the conductivity was stable. The method can be used in solar cells, flexible LED, intelligent packaging and can replace the traditional screen printing method at low cost.