Lost circulation controlling & killing material has been a focused issue since a long time ago.A novel leak resistance fluid with the raw materials such as SDS,SDBS,HES,PAM and proprietary productions has been developed from laboratory.The experiment and application shows that the new leak resistance fluid can plug leaking passage of different sizes simultaneously.Observing with 1000 to 2000 time microscope,it is found that the working liquid contains a kind of spherical material which has the microstructure of “one core,two layers,and three membranes”.When it is in a static state,the inside of the material looks like an airbag and the outside looks like some fuzzy things which has high gel strength.While when it is in a dynamic state,the fuzzy thing is cut or scattered and flow ability becomes much better.That is the reason why it is called fuzzy-ball.When the diameter or the width of the leak passage is greater than the fuzzy-ball’s,the fuzzy-ball accumulates in conical shape to decompose the working fluid pressure of liquid column to achieve blocking;when the diameter or the width of the leak passage is equivalent to the fuzzy-ball’s,the fuzzy-ball changes from sphere to oval-shape to increase the resistance to the leak passage and plug the holes;when the diameter or the width of the leak passage is smaller than the fuzzy-ball’s,the leaks could be blocked up by the non-permeable membrane formed by the gel of high strength in the working fluid.In these cases,the leak passages of different sizes could be blocked comprehensively. Lost circulation has been a focused issue since a long time ago. A novel leak resistance fluid with the raw materials such as SDS, SDBS, HES, PAM and proprietary productions has been from laboratory. The experiment and application shows that the new leak resistance fluid can plug the leaking passage of different sizes simultaneously. Observing with 1000 to 2000 time microscope, it is found that the working liquid contains a kind of spherical material which has the microstructure of "one core, two layers, and three When it is in a static state, the inside of the material looks like an airbag and the outside looks like some airbag and the outside looks like some fuzzy things which has high gel strength. Whilst it is in a dynamic state, the fuzzy thing is cut or scattered and flow able will be much better.That is the reason why it is called fuzzy-ball. Whin the diameter or the width of the leak passage is greater than the fuzzy-ball’s, the fuzzy-ball accumulates in conical shape to de compose the working fluid pressure of liquid column to achieve blocking; when the diameter or the width of the leak passage is equivalent to the fuzzy-ball’s, the fuzzy-ball changes from sphere to oval-shape to increase the resistance to the leak passage and plug the holes; when the diameter or the width of the leak passage is smaller than the fuzzy-ball’s, the leaks could be blocked up by the non-permeable membrane formed by the gel of high strength in the working fluid. In these cases, the leak passages of different sizes could be blocked comprehensively.