A side-slotted nozzle type double sheet spacer grid for nuclear fuel assemblies. The spacer grid includes intersecting inner strips and four perimeter strips. Each inner strip has unit strip parts, each fabricated by integrating two unit sheet parts together into a single structure, such that the two unit sheet parts face each other and a nozzle type coolant channel is defined between the two unit sheet parts. Each perimeter strip is fabricated by integrating an inner thin sheet having the unit sheet parts with a flat outer thin sheet having a width corresponding to the width of the inner thin sheet into a single structure. The coolant channel has one or more outlets formed by cutting an upper portion of one of the two unit sheet parts of each unit strip part. Each unit sheet part has a slot longitudinally formed on each side surface of a spring that is projected from the unit sheet part to support a fuel rod within a four-walled cell. The spacer grid thus effectively deflects and mixes coolants together to improve the heat transfer effect between fuel rods and coolants, and enhances its strength to effectively resist laterally directed forces acting thereon, and remarkably improves spring performance of its fuel rod support parts, thus accomplishing desired soundness of the fuel assemblies.