The invention discloses a simple method for culturing haematococcus pluvialis to produce astaxanthin; the method comprises three culturing processes of narrow neck flask, plastic cask or Nylon bag, cement pit; each step passes through various physical and chemical environmental parameters, such as nitrogen and phosphorus contents, pH value, incubation temperature, illumination intensity, illumination time, exact adjusting and controlling measure of adding with halite or halogeno salt, H2O2 and FeCl2 and cell state, etc; each step has definite object, and reasonable control such that the haematococcus pluvialis has excellent vegetative growth, fast conversion of vegetative growth to non-vegetative growth, and accumulates much astaxanthin, thereby improving the efficiency and stability of culturing, converting and accumulating, and effectively preventing the pollution of mixed algae; because the invention is an open culturing and does not need closed photobioreactor, thereby greatly reducing the production cost and obviously improving the productivity, and open culturing haematococcus pluvialis to produce astaxanthin in large scale.