1.A mum died,with her 3 months's baby under her body.(There was a three-month old baby under a mother’s body.)
2.She has died when the rescuer found her.(She was already dead when the rescuer found her.)
3.She was overwhelmed by crushed house.( The crumbling house crashed down on the mother.)
4.Through gaps of those ruins,we can see her last posture.(We could see her last posture through the gaps of the ruins of crackling houses.)
5.Being on her knees,the upper part of the body was prostrate forward,with her hands on the ground to support body.(She kneeled down.Both of her hands pressed on the ground.)
6.That was something like an acient who was kowtowing,just looked eerie because she was out of shape by pressure.(I’m totally blinded on these words/m\)
7.The rescuers confirmed her death by touching her through the gaps of ruins.(This is weird.)
8.They shouted at the ruins again and again,knocked the bricks using the crowbar,but no response inside.(They shouted at the ruins repeatedly.)
9.Then the rescuing team went to next building,suddenly the leader ran back,calling "come here".(…)
10.He came to the body,stretched his hands under the woman (who stretched “his” hands?It seems to me that you mean “the body stretched his hands”.Scared.),feeling and touching (supposed to use past tense rather than present participle),then shouted loudly "there is someone,a baby,still living" (Maybe I should it’s too wordy here.).
11.Through some efforts,rescuers cleaned up the ruins carefully,which blocked her(incomplete description).
12.Under her body,lied her baby,who was wrapped in a small red quilt with yellow flowers scattered in red.He is about 3 or 4 months' old.(…)
13.Since well protected by mother's body,he is totally safe.(past tense)
14.He was sleeping on both ears when the rescuer carried him out,and his lovely and peaceful face warmed everyone around him.(…)
15.The doctor along with the rescuing team unfastened the quilt to check if the baby is all right,and he found there was a moible phone filled in the quilt.(…”filled in the quilt”?...)
16.The doctor looked at the screen subliminally,a written message was already there:"my dear baby,if you could live,don't forget how much I love you".(It’s a good idea to keep the mother’s original words,but a simple sentence such as “I love you,dear”,which,I personally think,is more concise and well,unforgettable.)
17.As a doctor,he experienced too much of parting for ever; but at this moment,he wept.(OK.As a doctor,who had experienced much about these before,however,tears still rolled down his face.)
18.The mobile was passed,every person who saw this message sheded tears.(If it is possible,please don’t use a lot of passive voices.)
19.(The last thing is,please don’t forget the consistency of tenses in your writings.As in this case,you’re talking about the past,therefore,you should use past tenses as necessary.)