The invention discloses a method for manufacturing non-gel lightweight high strength fiberboards, which comprises following steps: firstly, preparing raw materials, secondly, disassociating the raw materials, thirdly, mixing serous fluid, and fourthly subsequently manufacturing according to wet method fiberboard procedures. The concentration of the non-gel lightweight high strength fiberboards which are produced by the invention is only 0.40-0.60g/cm3, not only the maximum ecological benefits and economic benefits for reclaiming and utilizing waste paper are realized, but also the product can be recycled and utilized since the lightweight high strength fiberboards do not add cementing compound, and secondary pollution is not produced to environment. The method of the invention has the advantages that the method is easily realized, the operation is convenient, the manufacturing cost is only 70-90% of the fiberboards on market, the strength also reaches to or exceeds national standards, more importantly, waste water is not produced through using the technique, and employment opportunities are created, which is beneficial for promoting harmonious development of resources, ecology and society.