1. Preparation of compound trimethyl 3,3′,3″- phosphine triyl tripropionate Under the problem of mechanical stirring, 80% tetrahydroxymethylphosphorus chloride liquid solution (71.2 g, 0.30 mol) and ethanol (75ml) were contributed to a 250ml response flask, cooled with ice water as well as protected by nitrogen, and after that included with hydroxide Potassium (16.8 g, 0.30 mol) was dissolved in a service of 23ml of ice water, as well as the temperature rose slightly; then ethyl acrylate (90g, 0.9 mol) was included dropwise, and also the temperature level was managed at 35-40 ° C, a big quantity of strong was created, as well as the temperature level was kept stirring after going down. 4 hrs. Put 300 ml of ice water into the reaction option, filter with suction after mixing, wash the filter cake with ice water, as well as completely dry with suction to acquire 88 g of white solid (that is, compound trimethyl 3,3′,3″- phosphinetriyltripropylidene) acid ester), the return was 86.6%, which was made use of for the next reaction. The nuclear magnetic data of the gotten item were as complies with: 1HNMR (CDCl3, 400MHz): δ= 1.27( t, 9H), 1.75( t, 6H), 2.45( dt, 6H), 4.15( q, 6H). 2. Preparation of substance tris( 2-carboxyethyl) phosphine hydrochloride (TCEP hydrochloride). Under the problem of mechanical stirring, the trimethyl 3,3′,3″- phosphine triyl tripropionate (88 g, 0.26 mol) prepared by the above response and the focused 12 mol/L molar concentration were contributed to the 250 ml response flask. Hydrochloric acid (120ml, 1.44 mol) was warmed to 80 ° C with mixing, the solid was progressively liquified, the reaction was proceeded for 3 hours, mixed and cooled down with ice water to separate out a white strong, suction filtered, as well as the filter cake was recrystallized with distilled water to get white crystals, particularly 3. (2-carboxyethyl) phosphine hydrochloride, stove dried out, considered 57.2 g, yield 76.9%. mp174-176 ℃. Nuclear magnetic data are as follows: 1HNMR (D2O, 400MHz): δ= 2.57( dt,6 H), 2.88( dt, 6H).