The present invention relates to a long-stroke nanopositioning device, comprising: a piezoelectric tube; a quartz glass rod; two fixed seats being disposed on the ends of the piezoelectric tube and a piezoelectric actuator. Each of the fixed seats has a base for receiving at least one spring and a plurality of ruby balls. The quartz glass rod is gripped to the fixed seat by the ruby balls of the fixed seat wherein the gripping force is controlled by means of the spring. The piezoelectric actuator applies an input voltage to the piezoelectric tube to cause one end of the piezoelectric tube to have a relative displacement in a direction along the axis of the quartz glass rod. The present invention provides a nanopositioning device capable of long stroke displacements at the nanometer scale by controlling the input voltage of the piezoelectric actuator and the gripping force of the ruby balls.